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Full text of "Practical Organic Chemistry"

PRACTICAL
ORGANIC   CHEMISTRY

BY

JULIUS  B.   COHEN,  PH.D.,  B.Sc.

PROFESSOR OF  ORGANIC   CHEMISTRY,  THE   UNIVERSITY,  LEEDS
AND ASSOCIATE  OF THE OWENS COLLEGE

MACMILLAN   AND   CO.,  LIMITED
ST.   MARTIN'S   STREET,   LONDON
r

RICHARD CLAY AND SONS, LIMITED,,
BREAD STREET HILL, E.G., AND

.   BUNGAY,  SUFFOLK.

First Edition, 1900.
Reprinted 1904, 1907.
Second Edition^ 1908, 1910.

LIBRARY
v 'X   \.
x fi;_-v
PREFACE TO THE FIRST EDITION

THE present volume is an enlarged edition' of that published
in 1887, and has been completely rewritten. The preparations
have all been carefully revised, some of the former ones
omitted and many new ones introduced. The chief additions
are the introductory chapters on organic analysis and molecular
weight determinations, and an extension of the appendix.
The book does not aim at being a complete laboratory guide,
but is intended to provide a systematic course of practical in-
struction, illustrating a great variety of reactions and processes
with a very moderate outlay in materials and apparatus.
The objection may be raised that the detailed description of
processes makes no demand upon a student's resourcefulness
or ingenuity. It must be remembered, however, that the
manipulative part of organic chemistry is so unfamiliar to the
elementary student that he requires minute directions in order
to avoid waste of time and material. Until he..has acquired
considerable practical skill he cannot accomplish the experi-
mental work requisite for research, and repeated failures will be
apt to destroy his confidence in himself.
To satisfy, to a. legitimate extent, the prejudices of certain
examining bodies, who still adhere to the old system of testing
a student's knowledge of practical organic chemistry by means
of the qualitative analysis of certain meaningless mixtures, the
special tests for some of the more common organic substances
have been inserted. At the same time, an attempt has been
at the end of the appendix to systematise the analysis of
r

PREFACE TO THE FIRST EDITION

organic substances on a broader and therefore more rational
basis.

1 The present occasion seems opportune to direct attention to
the fact that one of the most familiar, most readily procurable
and most cheaply produced of all organic materials is placed
beyond the reach of many students by the heavy duty levied
upon it. May I, in the name of teachers of organic chemistry,
.appeal to the Board of Inland Revenue, on behalf of scientific
and technical education, to .provide institutions for higher
education in science with a limited quantity of pure alcohol
free of duty, thereby placing schools of chemistry in this
country in the same position as those on the Continent ?

In conclusion I desire to thank Dr. J. McCrae, who has
written the section on Ethyl Tartrate and the use of the Polari-
meter, Dr. T. S. Patterson, who has been kind enough to look
•over the proofs, and Mr. H. D. Dakin, who has given me sub-
stantial assistance in the practical work of revision.

J. B. COHEN.

THE YORKSHIRE COLLEGE,
October,   1900.
PREFACE TO THE SECOND EDITION

IN the former edition attention was drawn to certain
drawbacks which accompanied the study of practical organic
chemistry, among which the heavy duty on alcohol and the
unsatisfactory nature of the practical tests demanded by
public examining bodies were specially emphasised.
Teachers and students alike must welcome the changes which
have since taken place. An excise duty on alcohol used in the
laboratory is no longer exacted from students of science, and
substantial reforms have been introduced into practical examina-
tions.
One important feature in some of the new examination
regulations is the recognition of the candidate's signed record
of laboratory work. We are, in fact, beginning to discover an
inherent .defect in practical chemistry as an examination sub-
ject, namely, its resistance to compression into a compact
and convenient examination form.
The old and drastic method by which chemistry was made to
fit into a syllabus consisted in cutting out the core of the
subject, or in other words, in removing all the processes which
demanded time, skill, and some intelligence, and in reducing the
examination to a set of exercises in a kind of legerdemain. This
process has been to a large extent abandoned, but a residuum
of it s.till remains. It is to be hoped that the kind of practical
examination in organic chemistry, which consists in allotting
a few hours to the identification of a substance selected from
,a particular list, will in time be superseded or accompanied
by a scheme encouraging candidates to show, in addition
to tfceir note-books, evidence of skill and originality, as, for
viii             PREFACE TO THE SECOND EDITION
example, in submitting specimens of new or rare preparations, or
in presenting an account of some small investigation.
The present edition is much enlarged and contains new pre-
parations, reactions and quantitative methods, all of which have
been carefully revised. My object has been not to follow any
particular syllabus, but to present a variety of processes from
which a selection "may be made to suit the special needs of
different students.
My thanks are due to Mr. Joseph Marshall, B.Sc., and
several of my senior students, for their assistance in the work of
revision.
J. B. COHEN
THE UNIVERSITY, LEEDS.
July, 1908.
CONTENTS
ORGANIC ANALYSIS—                                                               PAGE
Qualitative examination     ..............       i
Carbon and Hydrogen..............       I
Nitrogen....................       2
The Halogens...................      3
Sulphur.....................       3
Phosphorus...................      3
Quantitative estimation...............       4
Carbon and Hydrogen..............      4
Nitrogen....................     13
The Halogens...........,......     22
Sulphur.....................     28
Determination of molecular weight.........     28
Vapour density method..............     29
Cryoscopic or Freezing-point method.......     32
Ebullioscopic or Boiling-point method.......     37
Molecular weight of acids............     43
Molecular weight of bases............     46
PREPARATIONS-—
General remarks..................     47
Purification of spirit................     48
Ethyl alcohol.........;.........     49
Potassium ethyl sulphate............   .     50
Crystallisation ......   r   ,..........     52
Ethyl bromide...................     54
CONTENTS

PREPARATIONS—                                                                    PAGE
Dehydration of liquids..............     56
Determination of specific gravity     .........     56
„              boiling-point..........     58
Ether......................     59
Purification of commercial ether     .........     61
Ethylene bromide.................     62
Acetaldehyde...................     64
Methyl alcohol..................     67
•Methyl iodide...................     68
Amyl alcohol...................     69
• Amyl nitrite....................     69
Acetone....................,   .     69
Chloroform....................     70
Acetoxime....................     71
Melting-point determination............     72
Acetic acid....................     74
Acetyl chloride..................     74
Acetic anhydride................'..     76
• Acetamide....................     77
Heating under pressure............ . . .     78
Acetonitrile....................     79
Methylamine hydrochloride (Hermann's reaction) ...     80
v Ethyl acetate . ..................     Si
Ethyl acetoacetate .................     83
Distillation in vacuo...............     84
Monochloracetic acid...............     87
Monobromacetic acid...............     89
Glycocoll.....................     90
Glycocoll ester hydrochloride........• ....     92
Preparation of hydrogen chloride.........     93
Diazoacetic ester.................     94
Diethyl malonate.................     96
Ethyl malonic acid.................     97
Chloral hydrate..................     99
Trichloracetic acid .......«........     99
•  Oxalic acid   .  „..................    loo
CONTENTS

PREPARATIONS—                                                                PAGE
*-M ethyl oxalate..................   101
Glyoxylic and Glycollic acids............   102
Palmitic acid...................   104
Glycerol    .............   ........   106
Formic acid....................   106
Distillation in steam...............    107
Allyl alcohol...................   109
Isopropyl iodide..................   no
Epichlorhydrin..................   in
Malic acid....................   112
Succinic acid...................   113
Tartaric acid...................   114
Ethyl tartrate...................   115
Determination of rotatory power..........    116
Racemic and Mesotartaric acid.........• .   .   122
Resolution of Racemic acid (Pasteur's method)  ...    123
Pyruvic acid....................    124
Citric acid....................    124
Citraconic and Mesacomc acid..........    125
" Urea.......................    126
Thiocarbamide..................    128
Uric acicl.....................    128
Alloxantin....................    129
Alloxan......................    130
« Caffeine.....................    [31
Creatine.....................    132
Tyrosinc and Leucine (E. Fischer's ester method)  ...    133
Grape sugar....................    135
Benzene.....................    136
Purification of Benzene..............    136
Fractional distillation...............    136
• Bromobemene...................    14°
Ethyl benzene........      ..........    14*
-Nitrobenzene...................    U2
Azoxybenzene...................    !43
Electrolytic reduction of Nitrobenzene.......    144
CONTENTS

PREPARATIONS—                                                                    PAGE
Azobenzene....................J45
Electrolytic reduction of Nitrobenzene.......    145
Hydrazobenzene..................146
Benzidine....................    148
Phenylhydroxylamine...............148
Nitrosobenzene.................    149
^-Aminophenol................   .    149
/  Aniline......................149
Acetanilide.............'.......151
^-Bromacetanilide..................152
^/-Nitraniline...................153,
~;;/-Dinitrobenzene.................154
* 7;z-Nitraniline   .   ..................154
;/z-Phenylenediamine...............    155
Dimethylaniline..................    156
,..  /-Nitrosodimethylaniline..............    157
-Thiocarbanilide..................    159
s Phenyl thiocarbimide..............    160
""""'    Triphenylguanidine...............    160
Diazobenzene sulphate...............    161
Toluene from/-toluidine..............    ^3
/-Cresol.....................  ' !64
/-Chlorotoluene..................    ^
/-Chlorobenzoic acid .   ...............    155
/-Bromotoluene..................    267
/-lodotoluene................          <    j^g
Tolyliodochloride................    j5^,
lodosotoluene.................    !5o
p -Tolylcyanide..................    !59
/-Toluic acid................           l ^Q
Terephthalic acid............              ljl
Diazoaminobenzene...............       171
Aminoazobenzene.............                 j^^,
Phenylhydrazine................          I7^
Phenyl methyl pyrazolone (Knorr's reaction)    ....    175
Sulphanilic acid..............                 I-
CONTENTS

PREPARATIONS—                                                               PAGE
Methyl orange.................• .   176
Potassium benzene sulphonate...........   177
Benzenesulphonic chloride......•.......   178
Benzene sulphonamide..............    179
Phenol......................   179
Anisole......................   181
Hexahydrophenol (Sabatier and Senderens5 reaction)    .   181
•0- and ^-Nitrophenol................   i|3
Picric acid....................   185
Phenolphthalein...................^86
Fluorescein and Eosin...............   187
Salicylaldehyde and ^-Hydroxybenzaldehyde (Reimers
reaction).......•............   188
Salicylic acid (Kolbe's reaction)...........   190
Quinone and Quinol................   192
"Benzyl chloride..................   194.
Benzyl alcohol     ..................   195
Benzaldehyde...................   196
a- and /3-Benzaldoximes    ..............   197
Benzoic acid...................   199
Nitro-, Amino-, and Hydroxy-benzoic acid  ......   200
w-Bromobenzoic acid...............   201
Benzoin     .....................   202
B-enzil.......................   203
Benzilic acid...................   203
Cinnamic acid (Perkin's reaction)..........   204
Hydrocinnamic acid.........•.......   204
Mandelic acid...................   205
Phenyl methyl carbinol (Grignard's reaction).....   206
Benzoyl 'chloride..................   208
-   Benzamide...................   209
Ethyl benzoate..................   209
Quantitative hydrolysis of ethyl benzoate......   210
Acetophenone (Friedel-Crafts' reaction).......   210
Acetophenoneoxime...............   211
•Acetophenonesemicarbazone...........   212
xiv                                 o>.vn-:.\r>

PREPARATIONS -

Beckmann's reaction .........   .   .   .   .

Benzoylacetone (Clai^cn's read. ion      ...
Diphenyl methane   .........   ...

Triphenyl methane  ...........   .       .

Malachite green  ............

Naphthalene    ............   .   .

Phthalic acid   .............

/8-Naphthalcncsulphoiit'ite of sodium .......

/3-Naphthol  ..................

Estimation of methoxyl (XciscPs nu'th-h!} ,

„           ,, acetoxvl (A. ( 1.  IVrhin'-i im-Mi'i!

„         „  hydroxyl (TscIui^.u'f'f'N HK'tliti ;

Naphthol yellow ..............

*.**^ Anthraquinonc    ......   ....   .....

Anthraqtiinone ^-inonosulphouiite of^iuliMu,    .
Alizarin ...........   .....

Isatin from indigo  ..........   .   .   .

Quinoline ...........   ........

Quinine sulphate from r.inrhoiKi h.nk     ....

Phenylmethyltriaxole carhoxylii • ,i« id     .   .   .

APPENDIX.    Notes on the PrepariilinD-n   .....
HINTS ON THE INVESTIGATION or < M.:«; \\ir s? i; i \v
TABLES    ..........  ....

IN-DEX

PRACTICAL
OKCANU:  CHKMiSI
ORGANIC  ANALYSIS

Qualitative Examination.
Carbon and Hydrogen.—Carbon compounds are fre-
quently inflammable, and when heated on platinum foil take
fipe or char and burn away. A safer test is to heat the substance
with some easily reducible metallic oxide, the oxygen of which
forms carbon dioxide with the carbon present. Take a piece of
soft glass tube about 13 cm. (5 in.) long, and fuse it together
at one end. Heat a gram or two of fine copper oxide in a
porcelain crucible for a few minutes to
drive off the moisture, and. let it cool
in a desiccator. Mix it with about
one-tenth of its bulk of powdered sugar
in a mortar. Pour the mixture into
the tube, the open end of which is now
drawn out into a wide capillary and
bent at the same time into the form                FIG. i.
shown in Fig.   i.     This is done by
shaking down the mixture to the closed end and revolving the
tube in the blow-pipe flame about 2^ cm. (i in.) beyond the
mixture until it is thoroughly softened. The tube is then
removed from the flame, drawn out gently and bent. Make a
file scratch across the end of the capillary and break it. When
the. tube is cold tap it horizontally at the edge of the bench, so
as to &rm a free channel above the mixture. Suspend it by a
COHEN'S ADV. p. o. c.                                               B
PRACTICAL ORGANIC  CHEMISTRY

copper wire to the ring of a retort stand, and let the open end
dip into lime or baryta water. Heat the mixture gently with a
small flame. The gas which bubbles through the lime water
turns it milky. Moisture will also appear on the sides of the
tube, which, provided that the copper oxide has been thoroughly
dried beforehand, indicates the presence of hydrogen in the
compound. Gases, or volatile substances like ether and
alcohol, cannot, of course, be examined .in this way ; but
an apparatus must be arranged so that the gas or vapour is
made to pass over a layer of red hot copper oxide and then
through the lime water.
Nitrogen.—Many organic nitrogen compounds when
strongly heated with soda-lime give off their nitrogen in the
form of ammonia. Grind up a fragment of cheese or a few
crystals of urea with 5 to 6 times its weight of soda-lime, pour
the mixture into a small test-tube (preferably of hard glass) and
cover it with an equally thick layer of soda-lime. Heat strongly,
beginning at the top layer. Ammonia is evolved and can be
detected by the smell, or by holding a piece of moistened
red litmus paper at the mouth of the tube. When nitrogen is
present in direct combination with oxygen, as in the nitro- and
azoxy-compounds, ammonia is not evolved. The following
general method is applicable to all compounds and is there-
fore more reliable. The compound is heated with metallic
potassium or sodium when potassium or sodium cyanide
is formed. The subsequent test is the same as for cyanides.
Pour' about 10 c.c. of distilled water into a small beaker.
Place a fragment of the substance in a small test-tube along
with a piece of metallic potassium or sodium the size of
a coffee bean, and heat them at first gently until the re-
action subsides, and then strongly until the glass is nearly
red-hot. Then place the hot end of the tube in the small
beaker of water. The glass crumbles away, and any residual
potassium is decomposed with a bright flash, all the cyanide
rapidly goes into solution, whilst a quantity of carbon remains
suspended in the liquid. Filter through a small filter into a test-
tube. Add to the clear solution a few drops of ferrous
sulphate solution, and a drop of ferric chloride, boi'l up for
a minute, cool under the tap, and acidify with dilute hydro-
chloric acid. A precipitate of Prussian blue indicates the
QUALITATIVE  EXAMINATION

presence of nitrogen. If the liquid has a blue colour, let it
stand for an hour and examine it again for a precipitate. If no
precipitate appears and the solution remains of a clear
yellowish-green colour, no nitrogen is present.
If sulphur is present, an excess of alkali metal must be
used to prevent the formation of sulphocyanide.
The Halogens.—Many halogen compounds impart a green
fringe to the outer zone of the non-luminous flame. A more
delicate test is to heat the substance with copper oxide
(Beilstein). Heat a fragment of copper oxide, held in the loop
of a platinum wire, in the outer mantle of the non-luminous
flame until it ceases to colour the flame green. Let it cool down
a little and then dust on some halogen compound (brom-
acetanilide will serve this purpose, see Prep. 55, p. 152). Now
heat again. A bright green flame, accompanied by a blue zone
immediately round the oxide, indicates the presence of a
halogen. The halogen in the majority of organic compounds
is not 'directly precipitated by silver nitrate. Only those
compounds which, like the hydracids and their metallic salts,
dissociate in solution into free ions give this reaction. If,
however, the organic compound is first destroyed, and 'the
halogen converted into a soluble metallic salt, the test may be
applied. JHeat the substance with a fragment of metallic sodium
or potassium as in the test for nitrogen, p. 2. The test-tube
whilst hot is placed in cold water, the alkaline solution filtered,
acidified with dilute nitric acid and silver nitrate solution added.
A curdy, white or yellow precipitate (provided no cyanide is
present), indicates a halogen. If a cyanide is present, boil with
nitric acid until the hydrogen cyanide is expelled and add
silver nitrate.
Sulphur.—The presence of sulphur in organic compounds
may be detected by heating the substance with a little metallic
sodium or potassium. The alkaline sulphide, when dissolved in
water, gives a violet colouration with a solution of sodium nitro-
prusside. Heat a fragment of gelatine with a small piece of
potassium in a test-tube until the bottom of the tube is 'red hot,
and place it in a small beaker of water as described in the test
for nitrogen (p. 2). Filter the liquid and add a few drops of
sodium nitroprusside solution.
Phosphorus.—The presence of phosphorus is ascertained
4                PRACTICAL ORGANIC  CHEMISTRY

by heating the substance strongly with magnesium powder and
moistening the cold product with water. Magnesium phosphide
is formed and is decomposed by the water, giving phosphine
which is readily detected by its smell.

Quantitative Estimation.

Carbon and Hydrogen.—The principle of the method is
that described under qualitative examination^ but the substance
and the products of combustion, viz., carbon dioxide and water,
are weighed. The following app'aratus is required.

1.  An Rrlenmeyer or other form of Combustion Furnace.—
The usual length is 80-90'cm. (31-35 in.), and it is provided with
30 to 35 burners.    Flat flame burners are undesirable.

2.  A Drying Apparatus.—A form of drying apparatus which
is easily fitted together is shown in Fig. 2.    It consists of four

large U-tubes arranged side by side
in pairs. The U-tubes are mounted
upon a wooden stand with two up-
rights, to which the two pairs of tubes
are wired. The first of each pair is
filled with soda-lime, and the second
with pumice soaked in concentrated
sulphuric acid. Each soda-lime tube
is connected with a sulphuric acid tube
by well-fitting rubber corks and a bent glass tube. The two
other limbs of the sulphuric acid U-tubes are joined by a three-
way-tap forming a T-piece. The free end of the T-piece is
attached to a small bulb
tube, Fig. 3, containing a
drop of concentrated sul-
phuric acid to mark the
rate at which the bubbles
are B^.bg' through the                         FIG. 3.

iratus.      The

is. connect§$, \with the combustion tube by a short
M/ce of rubber tuning and a short glass tube, which passes
through a rubber cork fixed in the end of the combustion tube.
The rubber ".tubing carries a screw-clip. The open eno*s of

FIG. 2.

QUANTITATIVE  ESTIMATION

the soda-lime U-tubes are closed with rubber corks, through
which pass bent glass tubes. One of these glass tubes is con-
nected by rubber tubing to an oxygen gas-holder or to a
cylinder of compressed oxygen, which must be furnished with
an automatic regulating valve, and the other glass tube is
attached to a gas-holder containing air. By turning the three-
way tap, either oxygen or air may be supplied to the combustion
tube.

3. A Combustion Tube of Hard Glass.—It should be about 13
mm. inside diameter, and the walls not more than 1*5 mm.
thick. Its length should be such that it projects at least 5 cm.
(2 in.) beyond the furnace at either end. After cutting the
required length, the ends of the tube are carefully heated in the
flame until the sharp edges are just rounded. The tube is filled
as follows. Push in a loose asbestos plug about 5 cm. (2 in.) from

FIG. 4.
one end. This end, to which the calcium chloride tube and potash
apparatus are subsequently attached, maybe called the/r^/ end.
Pour in coarse copper oxide at the opposite end and shake it down
to the plug until there is a layer about two-thirds the length of the
tube. Keep the oxide in position by another plug of asbestos ;
see that the plugs are not rammed too tight. Make a roll of
copper gauze about 13 cm. (5 in.) long to slide easily into the
back end of the combustion tube. This is done by rolling- the
gauze .tightly round a stout copper wire until the requisite thick-
ness is obtained. The projecting ends of the wire are then
bent over into hooks as shown in Fig. 4. This roll, or spiral,
as it is usually called, is subsequently oxidised. It is pushed
into the tube or withdrawn as occasion requires by a piece of
hooked wire. The combustion tube is placed on a layer of
asbestos in the iron trough of the furnace. The arrangement of
the tube with boat and spiral is-shown in Fig. 5. *_ ;«,
4. A Straight Calcium Chloride Tube.—It is inserteatriroidgh a
rubber cork and fixed in the front end of the combustion tube
when the latter is not in use, as copper oxide is very hygro-
scopic, and it is necessary to protect it from the moisture in
the air.
PRACTICAL ORGANIC CHEMISTRY

5. A Potash Apparatus.—Several forms of potash apparatus
are made ; that of Geissler (Fig. 6), and Classen (Fig. 7) being
perhaps most commonly employed. The latter has the advan-
tage of being very light. The removable side tube is filled
with granulated calcium chloride or soda-lime, with a plug of
cotton wool at each end. The bulbs of the apparatus are filled

FIG. 5

with a strong solution of caustic potash containing 25 grams of
potash to 50 c.c. of water. This is done as follows. Remove
the soda-lime tube and attach in its place a piece of rubber             !

tubing.     This   serves   as a mouthpiece.     Pour   the   potash             ;

solution into a basin and dip the other end of the potash
apparatus under the liquid. Suck at the rubber tube until the             V

quantity appears   sufficient to  fill   the bulbs.     Remove   the             ¥

potash solution and continue to suck until the solution is trans-
ferred to the bulbs. The bulbs should be nearly filled. In the
case of Classen's apparatus, the liquid should stand half an inch
deep in the bottom of the apparatus outside the lowest bulb.

Wipe the potash solution from the outside and inside of the
inlet tube of the apparatus with filter paper. Smear a thin film
of vaseline on the ground end of the soda-lime tube before
replacing it, and fit to the open ends of the apparatus, stoppers
of rubber and glass rod, which are not removed, except when
the apparatus is in use. As the potash apparatus has jo be
QUANTITATIVE  ESTIMATION

FIG. 8.

refilled after every two combustions, it is advisable to keep a little
stock of solution in a bottle fitted with an ordinary cork.

6. A Calcium Chloride U- Tube.—The form of calcium chloride
tube is shown in Fig. 8. It is fitted with sieved calcium
chloride to within 2^ cm. (r in.) of the
side pieces, and then with coarser pieces
to within ^ cm. (£ in.). Place a small
plug of cotton wool in both limbs above
the chloride to keep it in position. Two
well-fitting corks, cut off level with the
glass and coated with sealing-wax, pro-
duce an effective air-tight stopper to the
open limbs, but it is preferable to seal

them in the blow-pipe flame. The sealing requires a little skill.
Carefully wipe off any chloride dust which may have adhered
to the open ends of the two limbs. Cork up one limb and
stopper one of the side tubes. Attach a short piece of rubber
tubing to the other side tube to serve as a mouthpiece. Now
soften the end of the open limb in a small blow-pipe flame, and
at the same time heat the end of a short piece of glass rod.
With the hot end of the rod gather up the edges of the open
limb, and whilst rotating the limb backwards and forwards in
the flame, draw it out and seal it up. If successful, the appear-
ance of the tube is that shown in Fig. 9. The blob of glass is
heated in a small flame, and, by gently blowing and re-heating

and blowing again, the blob can be
removed, and, finally, by using a
rather larger flame, heating and
blowing alternately, the end is
neatly rounded.

7. A  Porcelain or, preferably^ a
Platinum Boat.—See that it slips
easily into   the   combustion   tube.
The boat is  kept  in  a desiccator
on a flat cork or support made of glass rod when not in use.

Preparation of the Tube.—Before starting the com-
bustion it is necessary to clean and dry the combustion tube.
This is effected by heating the whole length of the tube con-
taining the copper oxide and spiral gradually to a dull red heat,
and passing through it a slow stream of dry oxygen from the

FIG. 9.
PRACTICAL ORGANIC CHEMISTRY

gas-holder or cylinder.   As soon as a glowing chip is ignited at
the front end and the moisture, which at first collects there, has
disappeared,- the gas jets are turned down  and  finally   ex-
tinguished.    The oxygen  is then stopped,   and  the  straight
calcium chloride tube inserted into the open end of the tube.
* Preliminary Operations.—Grind up a little pure oxalic
acid, and carefully weigh out 0-15 to 0*2 gram (not more) in the
boat   Weigh also the calcium chloride tube and potash appa-
ratus without stoppers or other accessories.    The side tube of
the calcium chloride tube, which carries the bulb, is attached
directly to the combustion tube with a rubber cork.    This cork
should be carefully selected, and should exactly fit the com- •
bustion tube.   The bore hole should be small and smooth, and
it is advisable to dust it with graphite or coat it with a film of
vaseline to prevent the rubber from clinging to  the glass, a.
matter of frequent occurrence unless this precaution is taken.
The cork should be kept exclusively for the combustion.   Push
the side tube of the calcium chloride tube through the hole until
it is flush with the opposite surface, and squeeze the cork tightly
into the combustion tube.   Attach the potash apparatus to the
other limb of the calcium chloride tube by a well-fitting piece
of rubber tubing about 3 cm. (i£ in.) long, and bring the ends
of the glass as closely as  possible  together.     It   should  be
unnecessary to wind wire round the joint if the rubber is of the
right diameter.   A little vaseline may be used here with advan-
tage, but only in the thinnest film.    The potash apparatus
will require to be supported upon a block or stand.    Remove
the copper spiral from the back of the tube.    Introduce the
boat and push it into position against  the asbestos plug by
means of the spiral which is placed behind it.    Replace the
rubber cork connected with the drying apparatus. The apparatus
will present the appearance shown in Fig. 10.
It must now be tested to see that it is air-tight. For this
purpose, close the open end of the potash apparatus with a
tight stopper and turn on the full pressure from either gas-
holder. After the first few bubbles of air have passed through
the bulbs of the potash apparatus no further movement of
bubbles should appear in any part of the apparatus. If it
withstands this test, the combustion may proceed. Release the
pressure by closing the tap of the gas-holder, screwing i»p the
QUANTITATIVE I

R r k R Y

clip at the back of the combustion\^,^rrd^cautiouslyremovimr
the stopper from the potash apparatus^ 'S^^f^^^r^^i
way tap from its socket for a moment. Sx^^n"^* '*• — ^ * ".,

The Combustion.—Turn on the oxygen ^TaSjusTthe rate
of flow through the apparatus by means of the screw-clip' so
that • 2 or 3 bubbles a second pass through the potash bulbs
Throw back the tiles if closed, and light the burners under the
front layer of copper oxide to within 10 cm. (4 in.) of the boat
and. also 2 or 3 burners under the spiral behind the boat, but
not within 5 cm. (2 in.) of the boat. Turn up the gas slowly to
avoid cracking the tube and in a minute or two, when the tube
is thoroughly warmed, close the tiles over the lighted burners
and heat to a dull red heat. A vivid red heat during the
combustion is not only unnecessary, but undesirable, as the
glass is apt to soften and be distorted and even to blow out and

FIG. 10.
become perforated. A combustion tuoe carefully handled
should last indefinitely. When the copper oxide is red hot,
turn on the burners very gradually from the spiral towards the
boat, but do not close the two pairs of tiles over the boat until
the combustion is nearly terminated and the burners are all
lighted. The first indication of the substance burning is the
appearance of a film of moisture at the front end of the
combustion tube and an increase in the speed of the bubbles
passing through the potash apparatus. The front end of the
tube, which should project 4 to 5 cm. (i-J- to 2 in.) from the
furnace, must be kept sufficiently hot to prevent moisture
permanently condensing there ; but it must never be allowed to
become so hot that there is any risk of the cork being burnt,
and it should always be possible to place the finger and thumb
found the part of the tube where the cork is inserted, A screen
^made 4rom a square piece of asbestos board, with a slit in it
PRACTICAL ORGANIC: CHEMISTRY

slipped over the tube at the end of the furnace, may be used
with advantage.                                           _
The speed of the bubbles is the best indication of the progress
of the combustion. If the rate increases so that the bubblesi
passing through the last bulb cannot easily be counted, ubunilvr
or burners must be lowered or extinguished until the spcjtxi
slackens. After a time, when the air has been displaced and
carbon dioxide largely fills the tube, the ps is nearly all ul>^
sorbed in the first potash bull). When this occurs, the current
of oxygen maybe increased until the bubbles appear synchro-
nously in the bulbs, when the current is again checked. £ f
some copper oxide has been reduced in the first stages of thCi
process, the bubbles in the potash apparatus may entirely ceust*
for a time, but will reappear when the copper has been reox|_
dised. Here again an increased current of oxygen will hasten
the process. The combustion is complete when a glowing chip
held at the end of the potash apparatus is rekindled All the*
moisture must by now have been driven over into the calcium
chloride tube. If this is not the case, warm the end of the (t(1.>^*
cautiously with a small flame, or by means of a hot tile held
near the tube The time required to complete the combust ion
is about one-half to three-quarters of an hour from the time- tlic*
front of the tube is red hot, but more volatile substances, whtcli
must be heated more cautiously, will naturally take longer,
The combustion being complete, gradually turn down, and in
a few minutes extinguish, the burners. Whilst the furnace cooln
the oxygen is replaced by a slow current of air. To do this *!*<,*
oxygen supply is stopped and the three-way tap is turner I
through 180°, so as to connect the tube with the air rcsm*t>it%
the tap of which is then opened and the stream of air rt»gulatt*cl
by the screw clip.
Let the air pass through for 20 minutes whilst the furnace •&
cooling down. Then remove and stopper the potash apparatus.
and'the calcium chloride tube, and after allowing them to stand
by the balance case for half-an-hour, weigh.
The results are calculated in percentages of carbon and
hydrogen as follows :
w is the weight of substance taken,
a is the increase in weight of the potash apparatus.     *
QUANTITATIVE  ESTIMATION

b is the increase in weight of the calcium chloride tube.
12 x a x 100

44 x w
2 x b x IPO

18 x~w~

=' per cent, of carbon.
= per cent, of hydrogen.

Example. — 0*1510 gram of oxalic acid gave 0*1055 gram of
CO2 and o-o68 gram of H2O.

I2X020S52LIOO =      0         cent of carbon.

44 xo'i5io

=   5-00 per cent, of hydrogen.
J      r                         &

18x0-1510
Calculated for C2H6Oa : C — 19 '04 per cent. ; H = 476 per
cent.
As a rule, the carbon is a little too low through loss of mois-
ture from the potash apparatus, whilst the hydrogen is too high,
probably through incomplete drying of the air and oxygen from
the gas-holders. The discrepancy should not exceed 0*2 per
cent, of the theoretical amount. If the substance burns with
difficulty it should be mixed with fine copper oxide in the
manner described under quantitative estimation of nitrogen.
The Combustion of Volatile and Hygroscopic Sub-
stances. — If the substance is a non-volatile liquid it may be
weighed in a boat like a solid ; if it is hygroscopic the boat
must be enclosed and weighed in a stoppered tube. If it is a
volatile liquid a glass bulb or tube, drawn out into a neck as
shown in Fig. 11, must be used. The
bulb is first weighed, and the liquid
is introduced by warming the bulb
gently to expand the air and then                FIG n.
inverting the   open  neck under the
liquid. The operation may require repeating. The tube is then
sealed and weighed again. Before introducing the bulb into
the tube the neck is nicked with a file and broken off. It
is then placed in the boat and pushed into the combustion
tube. In the combustion of a substance like naphthalene, which
is moderately volatile, the greater part is vaporised by the
heat of j;he copper oxide spiral in' contact with the boat. The
PRACTICAL  ORGANIC  CHEMISTRY

burners are therefore not lighted under the boat until towards
the close of the combustion. In the case of a highly volatile
compound like ether, a combustion tube is used, which projects
at least 15 cm. (6 in.) beyond the back of the furnace. The
bulb containing the substance is then placed just outside the
furnace, and then the spiral in contact with it. A small Bimsen
flame is placed under the end of the spiral away from the sub-
stance, the heat from which is sufficient to completely volatilise
the substance at a convenient speed.
The Combustion of Organic Substances containing-
Nitrogen.—The following modification must be introduced in
cases where the organic substances contain nitrogen. As the
nitrogen may be liberated in the form of one or oilier of its
oxides, which are liable to be absorbed in the potash apparatus,
a source of error is introduced, which may be eliminated in the
following way. A spiral of metallic copper is brought into the
front end of the combustion tube, which, when red hot, reduces
the oxides of nitrogen. The free nitrogen then passes through
unabsorbed. About 13 to 15 cm. (5 to 6 in.) of coarse
copper oxide is removed from the front end of the tube, and
after inserting an asbestos plug, the space left by the oxide 5s
filled with a roll of copper gauze 13 to 15 cm. (5 to 6 in.)
long. The copper spiral must have a clean metallic surface,
which is easily produced in the following way. Take a large
test-tube or boiling tube, an inch or so longer than the spiral,
and push down to the bottom a small pad of asbestos. I'our in
about 5 c.c. of pure methyl alcohol.
Have a cork at hand which fits loosely into the mouth of the
test-tube. Wrap the tube round with a duster. Hold the cop-
per spiral with the crucible tongs in a large blow-pipe flame until
it is red hot throughout and slide it quickly into the test-tube.
The methyl alcohol reduces the film of oxide on the copper ami
is at the same time oxidised to formaldehyde, the vapours of
which attack the eyes if the tube is brought too near the fare.
The alcohol takes fire at the mouth of the test-tube. When the
flame dies down insert the loose cork and let the tube cool. The
spiral, which has now a bright surface, is withdrawn, and tin-
excess of alcohol removed by shaking it. It must now be
thoroughly dried. Place the spiral in a hard glass tube a feu-
inches longer than the spiral and fitted at each end with a cork,
QUANTITATIVE  ESTIMATION

.nto which short, narrow glass tubes are inserted. Attach one
snd of the tube to an apparatus for evolving carbon dioxide,
ivhich is thoroughly dried by passing it through concentrated
sulphuric acid. When the air is expelled from the tube, heat it
gently until the alcohol is removed. Then let the tube cool
while the gas is passing through. The spiral is then removed
ind placed in the front of the combustion tube. The combustion
is carried out in the manner already described, but a current of
lir is substituted for oxygen until all the hydrogen has been
expelled, z>., until water ceases to condense in the front of the
:ube. The burners under the metallic copper are then gradually
2xtinquished, and the spiral allowed to cool whilst the current
D£ air is replaced by oxygen. By the time the oxygen reaches
:he spiral, the latter should have so far cooled that it remains
anoxidised. The current of oxygen is continued until a glowing
:hip is kindled at the end of the potash apparatus and the
operation is completed by turning on the air as previously
described.
A convenient substance to use for analysis is acetanilide, see
Preparation 54, p. 151.
Combustion of Organic Compounds containing
Halogens and Sulphur.—When the halogens or sulphur
are present in an organic compound, they are liable to be ab-
sorbed either in the free state or in combination with oxygen in the
potash apparatus. In this case, fused lead chromate broken up
into small pieces must replace the coarse copper oxide in the
combustion tube. The halogens and sulphur are retained by the
lead, the former as the halide salt, and the latter as lead sulphate
Special care must be taken in using lead chromate, that the
temperature of the furnace is not too high, as otherwise the
chromate fuses to the glass, and the combustion tube then
cracks on cooling.
Nitrogen (Dumas).—According to this method, a weighed
quantity of the substance is heated with copper oxide in a tube
filled with carbon, dioxide. The carbon and hydrogen form
respectively carbon dioxide and water, and the nitrogen which
is liberated in the form of gas is collected over caustic potash
(which absorbs the carbon dioxide) and measured.
The following apparatus-is required :—
l. A combustion furnace of the ordinary form.
PRACTICAL  ORGANIC C1IEMLSTRV

IMG. 12.

2. A short furnace of simple construction, such as ust-d in
Turner's method for estimating carbon in steel (Fig. 12). It
should carry an iron trough about
30 cm. (12 in.) long, iixed at such
a height that it can be heated by
an ordinary Bunsen burner.

3.  A combustion tuth\ which may
be   rather   longer   than  that,   used
in   the estimation  of carbon   and
hydrogen.

4.  A short Jtard s^Itiss ////V, 25
28 cm. (10—II in.) long", and closed at one end.

5.  A bent tube with a bull^ blown in the centre, as shown at
rt, Fig. 13.    This is attached by rubber corks to the cuds of the
long and short combustion tubes.

6.  A graduated Schffis Azotometer, Fig. 13............A small quan-
tity of mercury.is first poured into the bottom of the tube so as
to fill it 4—5 mm. above the lower side limb.    A solution  of
potash (i KOH : 3HaO) is then poured into the glass reservoir,
which is attached to the upper straight side limb by a  rubber
tube.    By raising the reservoir and opening the tap the tube is
filled, and remains so on closing the tap and lowering the reser-
voir.    When the tube is filled with potash solution then; should

be sufficient mercury at the bottom to seal off the potash solu-
tion from the bent limb, which connects with the combustion
tube.
7-  Two flasks, 200 c.c. ami 300 r.r.—Tlie necks are slightly
<-> XJ ANTITATIVE

ESTIMATION

constricted in
bustion tube
flasks are fitted

8.  A  spiral
reduced in
should be
and ready.
the spiral by
sufficient to \
and shake ofif

9.  A su
to fill the

blow-pipe flame, so that the end of the corn-
in as far as the constriction (Fig. 14).    The

3d corks.

copper gauze 15   cm. (6  in.) long, which is
alcohol as described on p. 12.    The spiral
just  before  use  when  the  tube is  filled
unnecessary to remove all the alcohol from
it in a current of carbon dioxide.    It is
it sharply through the air
excess of liquid.

giiantity of coarse copper oxide
tube two-thirds full and a

FIG. 14.

further quantity  of fine copper oxide to occupy
10—13 cm. (4-___£   In.) of the tube.
10.   Two   s/i.^z.llo'ii)   tin   dishes•,   ro—13   cm
(4—5 in.) in diameter for roasting copper oxide.
These dishes   oa-ra be obtained from.the iron-
monger in different sizes and are useful in the
laboratory for a, -v^ariety of purposes, such as for
oil, metal or sa/ncL-baths.
11.  A  squcz^tz    of copper gauze of moderate
mesh of the area,  of the tin dish.    It is turned
up at the edges    and is used for sifting the coarse from the
fine copper oxicle after each combustion.
12.  Pitre so^Zzzttn bicarboizate, NaHCO3, in powder free from
ammonia.
Filling th.0 Oombustion Tube.—A plug of asbestos is
first pushed in. fVom one end far enough to leave room for the
copper spiral? wliich should lie well within the furnace. This end
of the tube is subsequently attached to the azotometer and may
be called the /^o??t end. The coarse copper oxide is heated over
a Bunsen burntei- in one of the shallow tin dishes and the fine
oxide in anotlner. After about a quarter to half an hour the
burners are extinguished and the oxides whilst still warm are
introduced into their respective flasks with drawn-out necks,
The flasks are cl osed with corks and allowed to cool. The back
end of the combustion tube is now pushed horizontally into the
neck of the coarse oxide flask and the oxide poured on to the
plug by tilting- tlie flask and tube. The tube is filled with oxide
about two-thirds of its length. Into the flask containing the
16                PRACTICAL  ORGANIC  CHEMISTRY

fine oxide about 0*2 gram of powdered substance (acctanilide
may be conveniently used, see Prep. 54,  p.   151)   is weighed
out by difference from a sample tube, which should contain the
approximate quantity.    The substance is then well mixed with
the oxide by shaking the flask.     The contents of the flask are
carefully poured into the tube above the  coarse oxide  in  the
manner described and the flask is rinsed out with coarse oxide,
which is likewise poured into the tube until it is filled to the
full length of the furnace.     A loose plug of asbestos is pushed
in to keep the materials in position and the tube is   tapped
horizontally on the bench in order to form a channel above the
layer of fine copper oxide.    The tube is now laid in the furnace,
which is tilted a little forwards in order to collect the moisture
at  the front end   of the   tube.     The   short   closed   tube  is
well packed with powdered  sodium   bicarbonate  and   tapped
horizontally so as to form a good  channel   above  the   whole
length of the substance.    It is laid in the small furnace, which
is also tilted forwards to drain off the water which is formed.
The bicarbonate and the combustion tubes are connected by the
bulb tube already described.    The copper spiral is now reduced
and pushed into the front of the tube up to the plug and finally
the azotometer is attached by its bent tube.    The arrange men t
of the tubes and their contents are shown in Figs. 13 and 15.

The Combustion.—The tap of the azotometer is opem-cl
and the reservoir lowered so as to empty as far as possible the

COARSE   —   CuO

^^^SISSoiafa^uS^^fK'S^av^ff^

""•I

ASBESTOS
PLUG

JIG. 15.

'i

graduated tube.   ~"                                              *r

be       bv ,    ,                               paraUS   e»£ we" «*im:d,

end of L f" 7 >, ^ "* bicarbo"ate "<*r the closed
b v tiw i / Wlthag-°°d burner, and concentrate the heat
by tries placed on each side. A rapid stream of carbon d

s °       Wh !t

.                   eam  o    caron d
u±;s:; °nccr™-ved - Whr !t bee™ to <^,   £
rap d Ueam    Th         /" °rder to mai"^in a continuous and
iapid stieam.    The qmcker the stream of gas, the sooner is the
I

QUANTITATIVE  ESTIMATION                   17                 '.,:

_                  * _

air expelled, for the gas then pushes the column of air before
it like a piston, before the latter has time to diffuse.    In about
ten  minutes, the  row  of burners beneath the spiral and the
coarse oxide to within 10 cm. (4 in.) of the fine oxide may be
lighted.    In another fifteen minutes, the gas which is passing
through the tube may be tested.    The current is allowed to                     t   ^
slow down a little, and the graduated tube of the azotometer is                   -    • •
then  filled with potash solution by raising the reservoir and
closing the tap.    On gradually lowering the  reservoir, a  few
bubbles will pass up the graduated tube.
By the time they reach the top of the tube, the size of the
bubbles should have become so minute that when collected at the
top they occupy no appreciable volume, but appear as a fine froth.
If this is not the case, open the tap, run out the solution and
continue as before to drive carbon dioxide through the tube.
Repeat the test in another five minutes. Not more than half
the bicarbonate should have been utilised in expelling the air.
The air being removed, the combustion of the substance is com-
menced. The azotometer is filled with the potash solution, the
tap closed, and the reservoir lowered as far as possible. The
current of carbon 'dioxide is allowed to slacken, but it must not
be completely stopped. The front portion of the combustion
tube will by this time have reached a dull red heat. A few
more burners are now lighted on both sides of the fine oxide.
Finally, the layer of fine oxide is gradually heated and the pro-
cess conducted in much the same manner as that described
under the estimation of carbon and hydrogen. The combustion
is regulated by the speed of the bubbles passing up the
azotometer tube, which should enable them to be readily
counted. The burners being all lighted and the tube red hot
throughout, the tiles above the substance are closed. The
current of gas will shortly slacken. The residual nitrogen is
then expelled from the tube by moving on the flame beneath
the bicarbonate and causing a fresh stream of carbon dioxide to
sweep through the tube. Care must be taken that the stream
of gas is not too rapid, as otherwise the potash solution may
become saturated and driven completely into the reservoir. The                  ' ™
burners may now be extinguished and a reading of the level in
the azotometer taken every few minutes until it remains constant
and the bubbles are completely absorbed. Remove the
COHEN'S ADV. p. o. c.                                             c
iS               PRACTICAL  ORGANIC CHEMISTRY

azotometer by slipping out the cork from the front of the com-
bustion tube* and hang a thermometer beside it. Do not,
however, stop the flow of carbon dioxide until the tube is nearly
cold. In this way, the copper spiral remains quite bright and
may be used for a second determination without being
reduced.

When the azotometer has stood for an hour in a cool place,
adjust the level by raising the reservoir so that the liquid in the
tube and reservoir stand at the same height. Read off the
volume, and at the same time note the temperature and the
barometric pressure.

The percentage of nitrogen may be calculated as follows : —

v is the observed volume of nitrogen.
B is the height of the barometer in mm.
/ is the temperature.

/is the vapour tension of the potash solution, which may be
taken to be equal to that of water without serious error.

The volume corrected to o° and 760 mm. will be given by
the following expression : —

(273-{-/)76o

As the weight of r c.c. of nitrogen at o° and 760 mm is 0*00126
gram, the percentage weight of nitrogen will be given by the
expression

)       o'oor26x roo

where <w is the weight of substance taken.

Example.—o'2o6 gram of acetanilide gave iS'S c.c. of moist
X at if and 756 mm. [/at 17°== 14*5 mm.]

18-8 x 273 x (756-14-5) x 0-126 =        fi       cent

(273 4-17) x 760 x o'2o6
Calculated for CSH9ON ; N = 10-37 per cent.

Instead of collecting the gas over dilute potash solution, it is often
customary to use a very strong solution consisting of equal weights of
potash and water. The vapour tension is practically nil* Or, again,
the nitrogen may be transferred to a graduated tube standing over

r
QUANTITATIVE  ESTIMATION

water, which gives a result free from any error arising from incorrect
vapour tension. The manner of transferring the gas is shown in
Fig. 16. The stem of a wide funnel is cut off and attached by rubber
to the top- of the azotometer. This is then filled with water and the
projecting end of the azotometer is also filled with water. A graduated
tube is now brought over the end, and by opening the tap and raising



FIG. 16.

the reservoir the gas passes into the tube.    The end is now closed with
the thumb and transferred to a cylinder of water.
The tube is held by a collar of paper, whilst the level is adjusted
and the volume and temperature noted.
Before commencing a second determination, the contents of
the combustion tube are emptied on to the wire-gauze sieve,
placed over one of the tin dishes, and the fine and coarse oxide
separated. Both oxides are roasted in order to reoxidise any
reduced copper, and transferred as before to their respective
flasks. The sodium bicarbonate tube is emptied into, a special
C   2
20                PRACTICAL  ORGANIC  CHEMISTRY

bottle and then replenished with fresh material. Fresh caustic
potash solution is also introduced into the azotometer, unless
the stronger solution is used.

Estimation of Nitrogen^ Second Method.— Another method
which dispenses with the small furnace and bicarbonate tube
may also be used. The long" combustion tube is closed at one
end and magnesite in small lumps is introduced into the tube
and shaken down to the closed end until there is a layer of
about 13—15 cm. (5 — 6 in.). This is kept in place by a plug of
asbestos and the tube is filled successively with 5 cm. (2 in.) of
coarse copper oxide, then fine copper oxide mixed with the sub-
stance, a further layer of coarse copper oxide, and finally the

FINE      COARSE
COARSE        CuO _ QUO        CuO  MAGNESITE

I3cM.

ASBESTOS
PLUG

FIG. 17.

copper spiral. The contents of the tube are arranged as shown
in Fig. 17.
The magnesite (MgCO3), which evolves carbon dioxide on
heating, takes the place of the sodium bicarbonate in the
previous method. The air is displaced at the beginning by
heating the magnesite near the closed end of the tube. The
magnesite is again heated towards the end of the combustion to
sweep out the last traces of nitrogen. The disadvantages of
the method are that the magnesite requires to be heated much
more strongly than the sodium bicarbonate before it evolves
carbon dioxide, and the length of the layer of copper oxide is
curtailed.
Kjeldahl's Method. — The organic compound is heated
strongly with sulphuric acid,. which oxidises the organic matter
and converts the nitrogen into ammonium sulphate. The
ammonia is then estimated volumetrically by distilling with
caustic soda and collecting the gas in standard acid. About
0*5 gram of substance is accurately weighed and introduced into
a round Jena flask (500 c.c.), together with 15 c.c. of pure con-
QUANTITATIVE  ESTIMATION

lift

centrated sulphuric acid and about 10 grams of anhydrous
potassium sulphate. The object of the latter is to promote
oxidation by raising the boiling-point of the liquid. The flask is
clamped over wire-gauze and the contents boiled briskly until
the liquid, which first darkens in colour, becomes clear and
colourless or faintly yellow. When the decomposition is com-
plete (-£—i hour), the flask is left to cool and the contents then
diluted with 2—3 volumes of water. The flask is now attached
to the distilling apparatus shown in Fig. 18. It is furnished
with a double-bored rubber cork, through one hole of which a
bulb adapter is inserted (to re-
tain any alkali which may spirt
upwards), the latter being con-
nected with a condenser. The
end of the condenser just dips
below the surface of 25 c.c. of
a half-normal solution of hydro-
chloric or sulphuric acid, con-
tained in a flask or beaker. A
tap-funnel with a bent leg, con-
taining about 30 grams of
caustic soda in 60 c.c. of water,
is inserted through the second
hole in the cork. A few pieces
of porous earthenware or granu-
lated zinc are introduced into
the flask to prevent bumping.
After the apparatus has been
fitted together the caustic soda                      tlc> l8'

solution  is  run in slowly and

the flask shaken. The liquid is then boiled briskly until
no more ammonia is evolved (-|-—f hour). This should
be ascertained by testing a drop of the distillate with red
litmus paper. If the operation is complete, the liquid is
titrated with half-normal 'sodium carbonate solution, using
methyl orange as indicator.

Example.—0*5151 gram acetanilide required   17*3  c.c.  N/2
sodium carbonate :—

25 - 17-3 = 77-    77XO-OQ7XIOO =  IQ.46 per cent_
0-5151

if
*Y'
PRACTICAL ORGANIC  CHEMISTRY

The Halogens (Carius).—The method of Can"us, which is
usually employed, consists in oxidising the substance with fuming
nitric acid under pressure in presence of silver nitrate. The
silver halide which is formed is then separated by filtration and
weighed.

The following apparatus is required : —

i. A piece of thick-walled soft tubing about 45—48 cm.

iS__19 in.) long, and 12—13 mm. inside diameter, the walls

being at least 2-5—3 mm. thick. Tubes of hard potash glass are
also used, in which case the thickness of the walls may be rather
less. The tube is carefully sealed at one end so that there
is no thickening of the glass at any point into a blob. If a
blob is formed, it may be removed by heating it and blowing

FIG. 19.

gently into the tube and repeating the operation if necessary.
Tubes of soft or hard glass may be bought ready sealed at-
one end. The tube is. washed out and dried before use.
2.  A narrow weighing-tube, 8—ro cm. (3—4 in.) long and
sealed at one end, which will slip easily into the thick-walled
tube.
3.  Pure fuming nitric acid of sp. gr. 1-5.—This is prepared
by distilling equal volumes of concentrated nitric acid (150 c.c.),
and concentrated sulphuric acid (150 c.c.) from a litre retort, the
neek of which has been bent in the blow-pipe flame as in Fig. 19.
The object of this bend is to prevent acid from spirting into the
neck and being carried over mechanically into  the  receiver
during distillation.     The retort is placed on a sand-bath, and
QUANTITATIVE ESTIMATION

attached to a condenser. The acids are poured in through
a funnel, and a few small bits of broken unglazed pot are
dropped in to prevent bumping. The acid is distilled with a
moderate flame until about 70 c.c. have collected in the
receiver, when the operation is stopped. The distillate is then
tested for halogens by diluting largely with distilled water, and
adding silver nitrate solution. The liquid should remain per-
fectly clean It should also be tested for the presence of sul-
phuric acid, in case it is required for sulphur estimations, by

Ft

FIG. 20.

adding a few drops of barium chloride to a fresh portion of acid
diluted as above. If pure, it is kept in a stoppered bottle. If it
contains chlorine, it must be redistilled over a few crystals of
silver nitrate. Fuming nitric acid has a sp. gr. of about 1*5 at
15°, boils at about 90°, and contains about 90 per cent, of
HNO3. Acid of this strength can be purchased.
4. A Tube F-urnacc. — Various forms of furnace are used.
Those which are heated on the principle of the Lothar Meyer
hot-air furnace by a number of pin-hole gas jets are easily
regulated, and can be raised to a high temperature. The
Gattermann furnace, shown in the diagram (Fig. 20), is a very
convenient form.
PRACTICAL  ORGANIC CHEMISTRY

Filling and Sealing the Tube.—By means of a thistle
funnel with a long stem, about 5 c.c. of fuming nitric acid are first
introduced, and the funnel carefully withdrawn so as
not to wet the side of the tube.    About 0*5 gram silver
nitrate in crystals is dropped in, and finally the narrow
weighing-tube containing o'2—03 gram of substance
is slipped to the bottom  of the tube (see Fig. 21).
Bromacetanilide (see Prep. 55, p. 152) may be  used
for this estimation.     The open end of the tube is now
sealed  in  the  blow-pipe.     This   operation   requires
some care and a little skill.    About two inches of the
tube at the open end is very gradually heated by re-
volving it for several minutes in the smoky flame of
the blow-pipe.    The tube is now  grasped about the
middle with the left hand, and inclined at an an<'le of
about 45°.    The blast is turned on slowly, and the end
of the tube heated and revolved until the glass begins to soften.
The end of a glass rod, about 13 cm. (5 in.) long, held in the
right hand, is heated at the same time.    The glass rod is then

FiG. :

FIG. 22.

used to press the edges of the glass tube together, as shown in
Fig. 23. The subsequent operation depends upon whether
soft or hard glass is to be manipulated. If soft glass is used,
QUANTITATIVE  ESTIMATION

the blow-pipe flame is made as hot as possible, but reduced
in length to about 8 to 10 cm. (3 to 4 in,). It is directed at a
point about 2 to 3 cm. (i in.) below the open end to which
the glass rod is attached, the glass rod now serving as a support
whilst the tube is slowly rotated. The glass, if evenly heated
and not drawn out, begins to thicken where the flame plays upon
it, and the inside diameter of the tube contracts. When the
apparent inside diameter of the tube is reduced to about 3 mm.
(i in.), the tube is quickly removed from the flame, and a
capillary end formed by very slowly drawing out the thickened
part of the tube (Fig. 24). When the capillary has so far cooled
as to become rigid, it is sealed off. The tube will now have the

FIG. 23.

FIG. 24.

FIG. 25.

appearance shown in Fig. 25. The tube is kept in a vertical
position until cold. If the tube is of hard glass, a somewhat
different method of sealing is employed. As soon as the glass
is sufficiently soft, it is not thickened, but drawn out at once into
a wide capillary, about ij cm. long. By directing the flame
below this constriction, and continuing to draw out, the capillary
is further lengthened. When it has a length of 2 to 3 cm.
(i in.) it is thickened by revolving it in the flame and then
sealed off. Hard glass is much more easily manipulated in the
oxy-coal gas flame. When cold, the tube is transferred to the
metal cylinder of the-tube furnace. The furnace, conveniently
isolated in case of explosions, should stand on the floor, with
the open end raised and facing a wall. The capillary point



i
26                PRACTICAL  ORGANIC  CHEMISTRY
should project a little beyond the open end of the metal cylinder
in which the sealed tube is enclosed. The temperature, indicated,
by a thermometer fixed in the top of the furnace, is carefully
regulated. It is advisable to commence the operation in the
morning. The temperature is gradually raised from 150° to 200° -
during four hours, and then to 230° for a further four hours. The
gas is then extinguished, and the tube allowed to cool until the
following morning.
Opening the Sealed Tube.—The tube is drawn a little
way out of the iron casing, so that the capillary end projects
3 or 4 cm. The tip is then warmed cautiously in the Bun sen
flame to expel the liquid which as a rule condenses there. The
point is then heated until the glass softens, when the pressure
inside perforates the glass and nitrous fumes are evolved. O?i no
account must the tube be removed from the furnace before //its
operation is concluded. The tube is now taken away and
opened. A deep file scratch is made in the wide part of the
tube, about 3 cm. below the capillary. The end of a glass
rod, heated to redness, is then held against the file mark. A
crack is produced, which may be prolonged round the tube
by touching the tube in front of the crack with the hot end
of the glass rod. The top of the tube is now easily removed ; •
but in order to prevent fragments of glass from the broken
edge from dropping into the acid, the tube should be lielcl
horizontally and the end carefully broken off. Any bits of
glass which become detached adhere to the side of the tube,
near the open end, and can be easily wiped off. The contents
of the tube containing the silver halide are now carefully
diluted by adding water a few c.c. at a time, and then washed
into a beaker. The mixture is heated to boiling, the silver
compound transferred to a filter, and washed with hot water
until free from silver nitrate. The filter paper is then dried
in a steam oven and the silver salt weighed. A simpler and
more accurate method for filtering and weighing the silver
halide is to use a perforated or Gooch crucible. A disc of
filter paper is cut with a cork cutter of suitable dimensions
to fit the bottom of the crucible, which is dried with the crucible
in a Victor Meyer air-bath (Fig. 26) heated to 140—150° until
constant. The air-bath consists of a jacketed copper vessel
fixed upon a tripod. A liquid of constant boiling-point is poured
()UANTITATIYK   ESTIMATION

27

into the outer jacket and the vapours are condensed by an
upright condenser or tube which is attached to the outlet tube.
The crucible is placed within and
covered with a metal lid. There is a
small aperture to admit air from below
into the inner vessel and a corresponding
outlet in the lid. Aniline, b.p. 182°,
may be used in the outer jacket in the
present case. The (iooch crucible is
weighed and fitted to a filter flask and
the silver halide filtered and washed at
the pump. The crucible is -then heated
in the air-bath until the weight is con-
stant (^ hour) and weighed. The re-
sult is calculated in percentage of
halogen.

Extwiplc......Bromacetanilide gave  the

following result :-.......

o'l 5 i gram gave 0*134 gram AgHr.

l-'lli.   116.

• ==77-51 per
188x0-151        J        *

Calculated for CsIl,BrNO ; Hr = 37-38
per cent.

Another Method (Piria and Schrff).—There are some
substances which are incompletely decomposed with fuming
nitric acid under the conditions described above, and the results
are consequently too low. In such cases the following method
may be employed. The substance is weighed into a very small
platinum crucible, which is then filled up with a mixture of
anhydrous sodium carbonate (i pail) and pure powdered quick-
lime (4 to 5 parts). The crucible is then inverted in a larger
crucible, the space between the two being filled with the same
mixture of sodium carbonate and lime. The large crucible is
now heated, first with a small blow-pipe flame, and then
more strongly until the mass is red hot. The contents are then
allowed to cool, and dissolved in a large excess of dilute nitric
acid. The substance must be added slowly and the acid kept
cool. The halogen is then precipitated with silver nitrate and
estimated in the usual way.

I

L  J      V*    '

'SC

i,


28                 PRACTICAL  ORGANIC  CHEMISTRY

Sulphur (Carius). — The process is essentially the same as
that described under the estimation of halogens (p. 22). The
compound is oxidised in a sealed tube with fuming nitric acid,
but without the addition of silver nitrate. The resulting sul-
phuric acid is then precipitated and weighed as barium sulphate.
The same quantities of acid and substance (diphenylthiourea
may be used ; see Prep. 61, p. 159) are taken, and the process of
sealing up and heating, &c., are carried out in precisely the-
same way as for the halogens. The contents of the tube, after
heating, are cautiously diluted with water and then washed out
into a beaker, and filtered, if necessary, from fragments of glass.
The filter paper is then well washed with hot water and the
filtrate diluted to at least 250 c.c. with water. The liquid is
heated to boiling, and a few c.c. of barium chloride solution
added. On continued heating over a small flame the liquid
clears and the precipitate subsides. The addition of another
drop of barium chloride will determine if the precipitation is
complete. The liquid is then filtered through an ordinary
funnel, the precipitate of barium sulphate washed with hot
water, dried and weighed in the usual way.

Example. — Diphenylthiourea gave the following result : —

0*2518 gram gave 0*2638 gram BaSO4.

= 14*39 per cent.
233x0*2518

Calculated for C13H12N3S ; 8 = 14-05.

Determination of Molecular Weight

According to Avogadro's law, equal volumes of all gases
under similar conditions contain the same number of molecules.
Consequently the weights of equal volumes or the densities of
gases will represent the ratio of their molecular weights. If the
densities are compared with hydrogen as the- unit, the ratio

in which W8 and Wh are the weights of equal volumes of
substance anji hydrogen respectively, will give the molecular
weight of the substance compared with the molecule or two
atoms of hydrogen or half the molecular weight compared with
i'tr!l

DETERMINATION OF MOLECULR

one  atom   of hydrogen.     Consequently^ the  observed density
must be  multiplied  by two in ordeX^p" o]^s^-

weight compared with one atom of hydrog^L, "; •' V Q £[^ Q p- '**~ '.

Vapour Density Method (Victor" Meyer). —This
method, which is generally employed for substances which
volatilise without decom-
position, is known as the
air displacement method
of Victor Meyer. It con-
sists in rapidly vaporising
a known weight of a sub-
stance at a constant tem-
perature at least 40 — 50°
above its boiling-point in
a special form of appar-
atus, which admits of the
displaced air being col-
lected and measured. The
volume occupied by a
given weight of the sub-
stance under known con-
ditions is thus ascertained
and from these data the
density is calculated. The
following apparatus is re-
quired : —

I. A Victor Meyer Ap-
paratus as shown in
Fig. 27. It consists of
an elongated glass bulb
with a narrow stem, and
a capillary side-tube. It
is provided with a well-
fitting rubber cork, which

can be pressed easily and                        FIG. 27.

tightly into the open end

of the stem. The apparatus is clamped within an outer
jacket of tin plate or copper, which holds the boiling liquid
'required to produce a constant temperature. It is representeej^
as transparent in the Fig.                 y* \ ' \ _ . ••

"*':

I,



"D70

I     ..      •<    f
PRACTICAL ORGANIC CHEMISTRY

2. Hofmann Bottles.— The substance, if liquid, is introduced
into a small stoppered glass bottle known as a Hofmann bottle
''see  Fig. 28).    The dry bottle with  the stopper  is  carefully
&" weighed  and  then filled with liquid through a tube
^      drawn out into a wide capillary.    The stopper is in-
serted and the bottle reweighed.   It should hold about
o'i gram of substance.
3. A narrow graduated tube holding  50 c.c. and
divided into tenths of a c.c.
^         4. A large crystallising dish which serves as a gas
FIG. 28.   trough.
5. A long and wide cylinder in which the graduated
tube can be submerged in water.
6. A Bunsen burner with chimney.
The apparatus is set up as shown in Fig. 27. The Victor
Meyer apparatus is thoroughly dried by blowing air through by
means of a long glass tube, which reaches to the bottom of the
bulb. A small quantity of clean dry sand previously heated in
a crucible or a pad of asbestos is placed at the bottom of the
bulb to break the fall of the Hofmann bottle, when it is dropped
in. The bulb of the outer jacket is filled two-thirds full of
water and the displacement apparatus is clamped within it, so
that it nearly touches the liquid. The apparatus and jacket
must be adjusted at such a height that the capillary side limb
dips under the water contained in the crystallising dish, placed
on the bench. The graduated tube is filled with water and
inverted under the water in the crystallising dish and clamped
there until required. The burner protected from draughts by
the chimney is lighted under the outer jacket and the displace-
ment apparatus left open at the top. To avoid inconvenience
arising from the steam, a split cork, into which a bent glass tube
is inserted, is pushed loosely into the open end of the jacket.
Whilst the water is boiling steadily and not too violently, the
substance is weighed. Chloroform, b.p. 61°, or pure and dry
ether, b.p. 34-5° (see Prep. 3, p. 59), may be used for the
experiment, as their boiling-points lie well below that of water.
Before introducing the bottle and liquid, the apparatus must
be tested to ascertain if the temperature is constant. As
a rule \ hour's boiling suffices. Push in the rubber cork and
note if within the next minute or two any bubbles escape. If
DETERMINATION OF MOLECULAR WEIGHT         31

not, slip the graduated tube over the end of the side tube, and
carefully remove the rubber cork so that no water enters the
stem through the capillary. Remove the stopper of the
Hofmann bottle before dropping it in, and at once push in the
cork. Very shortly a stream of air bubbles will ascend the
graduated tube. When, in the course of a minute or two, the
bubbles cease, remove the cork from the apparatus and extin-
guish the burner. The graduated tube is transferred to the
large cylinder of water by closing the open end with the thumb.
Leave the tube in the water with a thermometer beside it
for J hour. Lift the graduated tube, and whilst holding it
by a collar of paper adjust the levels inside and out. Read off
the volume and note the temperature and barometric pressure.

The density is calculated as follows : —

If v is the volume, / the temperature, B the barometric
pressure, and f the vapour tension of water at /°, then the
corrected volume is given by the formula

_xJ^;/) x 273

This multiplied by 0*00009, the weight of i c.c. of hydrogen,
gives the weight of hydrogen occupying the same volume as

the vaporised  substance, from  which the density A= — *   is

A

obtained.

Example. — The following result was obtained with ether :
O"ii46 gram of ether gave 36*3 c.c. at 11° and 752 mm. /= 10
mm. at 11°.

36-3 x (752 - TO) x 273 x 0*00009 =
760 x 284

= 37.4
0-00306   0/ 4
Calculated for C4H10O ; A = 37.
If substances of higher boiling-point have to be vaporised,
the water in the outer jacket is replaced by other liquids of
correspondingly higher boiling-point, such as xylene, b.p. 140°,
aniline, b.p. 182°, ethyl benzoate, b.p. 211°, amyl benzoate, b.p.
260°, diphenylamine, b.p. 310°, &c. A Lothar Meyer air-bath
PRACTICAL  ORGANIC  CHEMISTRY

(Fig. 29) is, however, much more convenient for obtaining con-
stant temperatures up to 600°. It consists of three concentric
metal cylinders, the outer one being coated with non-conducting
material. They are so arranged that the heated air from a

movable ring burner passes be-
tween the two outer cylinders
(shown in section in the Fig.),
and descends to the bottom of
the central cylinder, into which
it has access through a ring
of circular holes. The hot air
is thoroughly mixed by this zig-
zag flow, and the temperature
is equalised. The bulb of
the displacement apparatus is
clamped in the interior cylinder,
and a thermometer is fixed be-
side it.

The vapour density of freshly
distilled aniline, b.p. 182°, may
be determined, the temperature
of the air-bath being adjusted
to about 240°. The adjustment is made by raising or lowering
the flame, or by altering the position of the movable ring-
burner.

Example.—0*1229 of aniline gave 31 c.c. at 7*5° and 750 mm.

FIG. 29.

A = 45-87.

Calculated for CCH7N ; A

46-5

The Cryoscopic or Freezing-point Method (Baoult).
—This method depends upon the fact, first demonstrated by
Raoult, and afterwards confirmed on theoretical grounds by
van't Hoff, that the original freezing-point of a given quantity
of liquid is lowered the same number of degrees by dissolving
in it different substances whose weights are proportional to
their molecular weights. This rule does not, however, apply to
salts, acids, &c., which appear to dissociate in certain solvents,
nor to substances which form molecular aggregates or associate
in solution. Supposing the freezing-point of 100 grams of a
DETERMINATION OF  MOLECULAR WEIGHT        33

solvent to be lowered i° by dissolving i, 2, 3 and 4 grams
respectively, of four different substances, the molecular weights
of these substances will be in the ratio of i : 2 : 3 : 4. In ordei
to convert these ratios into true molecular weights, the numbers
must be multiplied by a coefficient which depends upon the
nature of the particular solvent selected, and may be deter-                        £*

mined empirically by means of substances of known molecular                    1J \^

weight or by calculation from thermodynamical data.1                                    5"A 4

If w is the weight of substance and W^the weight of solvent,                         ''/, J

d the depression of the freezing-point, and k the coefficient for                          ''^,,

the solvent determined for the standard conditions, i.e., for the                        i" C*\

weight of substance, which produces i° depression in 100 grams                          '.'!'*'

of solvent, the molecular weight M is given by the following
expression:—                                                                                                                   «"*

If __ ! °° &W-                                                                   'I '.",',

_____                                                                     >'< ,

.' * i!»

The values of k for some of the common solvents with their                  *           $

melting-points are given in the following table :—•                                                     ' ^

|    m.p.
Water...         .........    !     o°

Nitrobenzene
Benzene
Acetic acid
Phenol...

5"3

5'4
17
40

/-Toluidine    .........    I    42*5

39 -o
72'°

It should be remembered that nitrobenzene, phenol, and acetic acid
are hygroscopic.
The following apparatus is required :—
A Beckmann Freezing-point Apparatus.—The form of appar-
atus is shown in the accompanying Fig. 30. It consists of a
glass jar standing on a metal tray and furnished with a stirrer.
The cover of the jar has a wide slit to admit the stirrer, and a
circular aperture with clips to hold a wide test-tube.
Within the wide test-tube is a narrower one, which is held in
position by a cork. The narrow test-tube is sometimes
*
1 Vide van't Hoflf, Ztscltr, pkys. Chcm., 1. p. 481 ; Ostwald, Outlines of General
Che»tistry} chap. vi. p. 139 ; J. Walker, Introduction, to Physical Chemistry, chap*
xviii. p. 176.
,COHEN'S ADV. P. o. c.                                            D
34

PRACTICAL  ORGANIC  CHEMISTRY

furnished with a side tube, for introducing the substance, but it is
not necessary. It is provided with a stirrer. A Beckmann
thermometer completes the apparatus. This is fixed through a

cork so that the bulb
nearly touches the bottom
of the tube, a wide slit
being cut in the side of
the cork for moving" the
stirrer. The Beckmann
thermometer is of special
construction and requires
explanation. As the
method involves merely
an accurate determination
of small differences of
temperature, it is not re-
quisite to know the exact
position on the thermo-
meter scale. The Beck-
mann thermometer regis-
ters 6 degrees, which are
divided into hundreclths.
The little glass reservoir
at the top (a, Fig. 30)
serves the purpose of
adjusting the mercury
column to different parts
of the thermometer scale
by adding or removing
mercury from the bulb.

Freezing-point De-
termination. — In  the
example to be described,
IMG. 3o.                          pure benzene (see p. 136)

is  used   as   the  solvent

Carefully dry the inner tube. Fit it with a cork and weigh it
together with the cork suspended by a wire to the arm of the
balance. Introduce sufficient benzene to cover the bulb of the
Beckmann thermometer when it is pushed nearly to the bottom
of the tube. About 10 c.c. will be found to be sufficient Insert

DETERMINATION OF MOLECULAR WEIGHT         35
the cork and weigh the tube and benzene. Fill up the outer jar
with water and small lumps of ice and stir from time to time.
Whilst the benzene is cooling in the apparatus the Beckmann
thermometer may be adjusted.
Adjustment of the Beckmann Thermometer.-—
Determine first the value of the mercury thread in degrees
between the top of the scale and the orifice of the reservoir.                    tr<
This may be clone by warming the bulb in a water-bath along                    \\%{
with an ordinary thermometer.    As soon as sufficient mercury                  '
has collected at the orifice, the burner is removed, the water                  ' ^i|
well stirred, and the little bead of mercury detached by gently
tapping the head of the thermometer without removing the bulb
from the water. The temperature on the ordinary thermometer                   /f|
is noted and is again read off when the mercury in the Beck-                    v'!/
mann thermometer has subsided to the top of the scale.     Sup-                    |\ ^
posing, then, the value of the thread above the scale to have                   '',/*';
iDeen determined and equivalent to 2°, and the freezing-point of                    i]/
benzene to be about 4°, the thermometer degrees may in this case                     \ *£
be made to coincide with the Beckmann degrees, which will bring                        >l'f "*
the thread of mercury well up the scale.    The bulb of the thermo-                      ^
meter will therefore require to be at a temperature of 64-2 = 8°                      $\
before removing the excess of mercury.    It will, however, be                       '1
necessary to introduce more mercury into the bulb.    This  is                        I
done by inverting the thermometer and tapping it gently on the                    »   ' ]
palm of the hand, so as to detach a bead of mercury, which                    •* J
slips down to the orifice of the capillary. By warming the bulb
the mercury is driven to the top and coalesces with that in the
reservoir, so that on cooling the additional mercury runs into
the bulb. When sufficient mercury has been added the thermo-
meter is cooled to 8°, and the excess detached as described above
The zero should now coincide approximately with that of ice-
cold water. If the thermometer is to be adjusted to any other
temperature it is placed in water and warmed to that tempera-
ture -h the number of degrees on the scale above that point
4- the value of the thread above the scale. The excess, of
mercury is then detached. The thermometer being adjusted,
insert it through the cork so that the bulb is well covered by the
benzene, and let the benzene cool well below its freezing-point
before stirring. Tap the head of the thermometer occa-
sionally with a pencil. Now stir briskly for a moment As soon
D 2
36                PRACTICAL  ORGANIC  CHEMISTRY

as crystals of the solvent begin to separate the mercury thread
will shoot up. Keep stirring occasionally and tapping the
thermometer, and read off the maximum point reached by means
of a lens. This gives a rough indication of the freezing-point
of the benzene. Take out the inner tube and melt the crystals
by warming the tube in the hand, and replace it in the apparatus.
Repeat the experiment, cooling the solvent not more than 0*2°
below its freezing-point before stirring. Make two or three
determinations in this way. The results should not differ by
more than o'or. Fuse some naphthalene in a basin and break
it up into small lumps or mould into pellets (p. 39). Weigh a
piece of about 0*1 to 0*2 gram on a watch-glass. Raise the cork
of the inner tube and drop the naphthalene in. Let it dissolve
and then determine the freezing-point of the benzene as before.
Repeat the process by dropping one or two fresh pieces of
naphthalene into the same solvent. At the end of the operation
remove the thermometer and stirrer, and weigh the benzene in
the inner tube with the cork. After deducting the weight of
naphthalene, the weight of the benzene will be approximately
the mean of the first and final weighings.

Example.—Using the same solvent and adding successively
three lots of substance (naphthalene), the following results were
obtained :—

W.              a.              M.        Mean.

0-0985
0-0729
0-1193

97

0-403
0-305
0-486

126

123-2

126-8

Calculated for ClftHR; M = 128.

In determining the molecular weight of liquids the apparatus
shown in Fig. 82 (p. 210) is convenient for weighing and trans-
ferring the liquid to the tube.
The Eykman Depressimeter.—For rapid but less
accurate determinations the apparatus of Eykman may be used,
which is shown in Fig. 31. It consists of a small vessel, into
the neck of which a thermometer is ground. The thermometer
is of the Beckmann type but divided into twentieths of degrees.
Phenol, m.p. 42*5°, is usually employed as the solvent. The
vessel and thermometer are dried and weighed. Phenol melted
on the water-bath is poured in to within about 5 c.c. of the neck,
DETERMINATION OF MOLECULAR WEIGHT

37

the thermometer inserted, and the apparatus weighed again.
The melting-point of the phenol must now he ascertained.
Warm the metal over a small flame on a sand-bath so as to
melt the phenol, leaving, however, a few crystals floating in the
liquid, and place the vessel in the cylinder, at the bottom of
which is a wire spring or pad of cotton wool. A perforated
cork at the top keeps the stem of the thermometer in position.
Let the phenol cool down well below its freezing-point, and
then shake the cylinder until solidification commences. This
will give a first approximation to the freezing-
point. The -phenol is now warmed gently as before
until only a few crystals remain unmelted. The
vessel is replaced in the cylinder and the liquid
cooled 0*5° to i° below the point previously ascer-
tained. It is now shaken until crystallisation sets
in, and then occasionally until the maximum point
is reached. The operation is repeated as often
as requisite. The substance is now introduced, a
sufficient quantity being taken to produce a depres-
sion of at least 0*5°. In order to effect this the
phenol is melted and the neck warmed with a
small flame until the thermometer is loosened and
can be withdrawn. As much phenol as possible
is allowed to drain off the neck and off the ther-
mometer, and the weighed quantity of substance
introduced. The thermometer is replaced, and any phenol which
may have run out is wiped off from the outside of the vessel, which
is then re-weighed. The freezing-point is determined as before.

The Ebullioscopic or Boiling-point Method
(Raoult).—The boiling-point of a liquid is found to be affected
by the presence of a dissolved substance in a similar manner
to the freezing-point, that is, the boiling-point of a given quantity
of a liquid is raised the same number of degrees by dissolving in
it the same number of molecules of different substances, or, in
other words, such weights of these substances as represent the
ratio of their molecular weights. These facts were first clearly
demonstrated by Raoult.

Statical Method.—The most convenient form of apparatus
for determining molecular weight by this method is Beckmann's
boiling-point apparatus shown in Fig. 32.

FIG. 31.
PRACTICAL ORGANIC

a

Jreflux

It

It consists of a boiling-tube, through the bottom"1
stout platinum wire is  sealed, which  is intended

external
liquid   an<
bles     at
Above
layer,   -
deep,   of
The     obj
beads   is   t°
the bubbles
vent superl
irregular
the side
condenser

to cornier* «e l^ va.
pours given oil clUrjng
the boiling- A Beck-
mann thcrnlometer is
inserted tliroug^ the

mouth of the tube.
This thermometer is
similar in <^onst*~Uction
to that used for freez.
ing-point c|ete*"inma-
tions, but it l^as a
smaller Ui-ilb. The
boiling--tul:>*^ is placed
in the central cavity
of a hollow gla.ss or
porcelain jtxcket, \vhich
contains the same
liquid as tlie "boiling-
tube and is also pro-
vided with. £t condenser.
This jaclcot prevents
radiation, fromtVie boil-
ing-tube.          It Is pro-
vided with two windows of mica. The jacket is c:li.xrnpecl on a
gauze ring supported on a square tray of asbestos plitced upon a

FIG. 32.
DETERMINATION OF MOLECULAR WEIGHT

tripod.    In the figure the lower part of the porcelain jacket and
the asbestos tray are made transparent to show the position of
the burners and the concentric rings of asbestos below the tray.
The asbestos  has a circular hole in the centre, which admits
the  lower end of the boiling-tube.     Two  asbestos  chimneys                   t | IL
are fixed upright at the diagonal corners of the tray to carry
off heated air and two burners are placed below the other two                     /i'l
corners.    The boiling-point of the solvent is first ascertained.                     |/|
For this  purpose  benzene  may be  used.        The  Beckmann                     fif
thermometer must be adjusted so that, when in the boiling liquid,                     !»11
the thread occupies the lower half of the scale.    In order to                    ;/4|
adjust it, the bulb must be placed in water warmed gradually                     '^|
6°—7° above the boiling-point of benzene, and the bead  then                    'tf '.
detached as already explained in the description of the freezing-                      \f
point method.                                                                                                 > ^
The boiling-tube is  carefully dried and  weighed with  the                     {4?
beads.     Sufficient benzene is poured in to cover the bulb of the         .             ;',<
thermometer, which is pushed down a little way into the beads.                      ^*
The condenser is attached to the side limb.    A layer of i—2 cm.                       fl
of benzene is poured into the outer jacket, and the condenser                      , $
fixed in position. The same water supply may be made to
traverse both condensers. The two burners under the tray are
lighted and the temperature regulated so that the benzene in the
outer jacket boils briskly, whilst at the same time sufficient heat
finds its way to the boiling-tube, through the gauze ring outside
the concentric screens of asbestos below the tray, to keep the
benzene in the state of steady ebullition. In about J hour from
the time the benzene boils in the inner tube the first reading may
be made, and a fresh reading every five minutes until the
temperature is constant, z>., does not vary more than 0*01°. As
the atmospheric pressure may produce considerable variations in
the reading, it is important to observe the barometer occasionally
during the experiment, and to make a correction, which is about
0*043° f°r every i mm. below 760.
The temperature being constant, a pellet (0*1—0*2 gram) of
fused naphthalene is carefully weighed and dropped into the boil-
ing-tube through the condenser without interrupting the boiling.
These pellets are conveniently made in a small bullet-mould.
The boiling-point will rise and after a few minutes will remain
stationary. The temperature is noted. A second and third
PRACTICAL  ORGANIC  CHEMISTRY

determination may be made by introducing fresh pellets of
naphthalene.

When the observations are complete, the apparatus is
allowed to cool and the weight of benzene ascertained by
weighing the boiling-tube and benzene.

As in the freezing-point method, the molecular weight is
calculated from the weight of substance required to raise the
boiling-point of ioo grams of solvent i°, and the result multiplied
by a coefficient which depends upon the nature of the solvent.
The following is a list of solvents commonly employed and
their coefficients and boiling-points :—'•

Ether

Acetone    ...
Chloroform
Methyl alcohol
Ethyl acetate

b.p.
	k.

35°
	2I'I

56°
	I7T

61°
	36-6

66°
	s-s

77°
	26-8

Ethyl alcohol
Benzene    ...
Water
Acetic acid
Aniline

bp.

78°

79°
100°
118°
184°

26-1

5*2

25'3

32-2

The molecular weight is determined from the formula

M - I0° kw
dW

in which w is the weight of substance,   W that of the solvent,
d the rise of boiling-point, and k the coefficient

Example.—Using the same solvent and adding successively
four pellets of naphthalene, the following results were
obtained :—

w
o
o*

O'

o-

W.                 d                M.
			
66
	21-313
	0-l8S
	126-6

93
	»j
	0-I85
	128 3

60
	3)
	0-I85
	126*0

01
	55
	0-180
	132-4

Calculated for C]0H8 ; M = 128.
			
Mean.

128-3

A simpler and more convenient form of Beckmann apparatus,
requiring much less solvent and giving equally accurate results,
is shown in Fig. 33. It consists of a boiling-tube furnished with
two side pieces, one of which is stoppered and serves to
introduce the substance and the other acts as a condenser. The
boiling-tube stands on an asbestos pad and is surrounded by
two short concentric glass cylinders surmounted by a mica plate.
The other parts of the apparatus are similar to those in the older
form and the process is conducted in the same way.
DETERMINATION OF MOLECULAR WEIGHT

Example—Ten c.c. of benzene were used and two pellets of
naphthalene were added.
W.

IV.

0-2072
0*2072

874
874

d.
0-483
0-485

Af.
131-1
127-6

Mean.
} 129-3

Dynamical Method.—A third, somewhat different and
less accurate, method for determining the boiling-point is one
devised by Sakurai and
modified by Lands-
berger and later by
Walker and Lumsden.
The apparatus of
Walker and Lumsden
is shown in Fig. 34,
and consists of three
vessels, a boiling flask,
A, a tube, B, graduated,
in c.c. and an outer
jacket of glass, c. The
boiling flask is pro-
vided with a safety
tube, D, and a bent
tube, E, which is con-
nected with another
bent tube, F, passing
through a cork to the
bottom of the gradu-
ated tube, B. A ther-
mometer graduated in
tenths is inserted
through a second hole
in the same cork. There is a small hole at G in the graduated
tube below the cork through which the vapour of the boiling liquid
escapes into the outside jacket, and is condensed by a condenser
not shown in the diagram. The outer jacket, c, is attached by a
cork surrounding B. A small quantity of solvent (5—10 c.c.) is in-
troduced into the tube B and a larger quantity of the same solvent
into the boiling flask, A. The vapour from A passes into B and
raises it to the boiling-point, which is read off. The excess
of liquid which has condensed is poured out The weighed .

FIG. 33.

^Jt


PRACTICAL ORGANIC  CHEMISTRY

substance is introduced and the boiling continued. When
a steady temperature is reached, the new boiling-point is
determined ; the tube is immediately disconnected from the
flask, the flame removed, and the volume of the solvent is
read off as accurately as possible. By repeating the process,

several determina-
tions may be car-
ried out with the
same solvent and
the same material.
The weighing of
fresh solvent for
each estimation of
new portions of
substance is also
avoided. The main
precautions to be
taken are (i) to
ensure steady boil-
ing in the flask, A,
by introducing frag-
ments of porous pot,
and (2) to conduct
the boiling at such
a rate that the drops
fall slowly and re-
gularly from the
FIG. 34.                              condenser. The in-

accuracies   of  the

method arise from constant change of concentration throughout
the operation and from impurity in the solvent, the boiling-point
of which will have a tendency to rise as the distillation proceeds.
Examples.—

Volume of solvent.1         d.         Jlf.   Mean.

1   I  0*8109 gem. (urea)

2   1  0-8109

17*5 c.c. (alcohol)

1-04

0-52

_             Calculated for CON2H4; M=6o.
l The constants for liquids at the boiling-point (= constant divided by the specific
gravity of the solvent at the boiling-point) are as follows :—
Alcohol    ......    i5'6o                Acetone    ......    22*20
Ether      .....     30*30                Chloroform     ...    26*00
Water     .....       5*40                Benzene.......    32*80
MOLECULAR WEIGHT OF ORGANIC ACIDS         43

Although the boiling-point method is able to dispose of a
greater number of convenient solvents than are suitable for
freezing-point determinations, it is never so accurate, mainly on
account of the difficulty of avoiding fluctuations in the boiling-
point, due to radiation, to the dripping of cold liquid from the
condenser, to impure solvent, and to barometric fluctuations.

Molecular Weight of Organic Acids                            '/{'
r f
Determination by means of the Silver Salt.—The               /j!|
basicity of an organic acid being known, the molecular weight                    (-ff
can be determined by estimating the amount of metal in one of                  is f
its normal salts.    The ratio of metal to salt will be that of the                   # *
atomic weight of the metal to the molecular weight of the salt.                   U\
The silver salts are usually selected for these determinations,                    iM]
since they are, as a rule, normal, i.e. neither acid nor basic ;                   ^ff
they are only slightly soluble in water, and are consequently                    ,/j^
readily obtained by precipitation, and finally they rarely contain                    |^|
water of  crystallisation.    On   the   other   hand  they are very                   1 j)
unstable, being quickly discoloured when exposed to light, and                   * >L
often decomposing with slight explosion when heated.    Silver
benzoate may be prepared by way of illustration.      Weigh out                       |f
roughly 2—3 grams of benzoic acid into a flask, and add about
20 c.c. of water and an excess of dilute ammonia.    Boil the
solution until the escaping steam has nearly lost the smell of
ammonia, and then test the liquid from time to time until it is
neutral to litmus. Cool the flask under the tap, and add an excess
of silver nitrate solution (3—4 grams AgNO3).     Filter with the
filter-pump.
Filtration under Reduced Pressure.—A filter-pump is
an essential part of a laboratory fitting. It consists of a good
water-jet aspirator (see Fig. 35), which is fixed to the water-tap
by a stout piece of rubber tubing well wired at both ends. The
joint is wrapped round with cloth or leather wired on to the
rubber. The side tube of the aspirator is connected by pump
tubing to an empty filter flask or bottle by means of a glass tap.
A second glass tube or side piece is put in connection with the
filter flask by means of rubber tubing. The object of inserting
a vessel- between the pump and the filter flask is to prevent
44

PRACTICAL ORGANIC CHEMISTRY

water running back when the aspirator is stopped. Before
stopping the pump, close the glass tap. Turn off the water, and
then lift the tap out of its socket for a moment to equalise the
pressure.

Use a porcelain funnel and filter flask, different sizes of which
are shown in Fig. 36. The bottom of the funnel is covered with
a disc of filter paper. After filtering, wash three or four times

with a little cold water,
press the precipitate
well down and let it
drain. Remove the
precipitate and spread
it on a piece of porous
plate, and place it in
a vacuum-desiccator
over sulphuric acid.
There are several use-
ful forms of vacuum-
desiccator, two of
which are represented
in Fig. 37.

The ground rims
are greased with vase-
line or a mixture of
bees-wax and vaseline,
and the air is exhausted
by attaching the tube
of the water-pump to
FIG. 35.                          the glass tap of the

desiccator.

If the substance is left overnight in the desiccator it will be
dry by the next day. The silver salt should be protected as far
as possible from the light. When the precipitate is thoroughly
dry, weigh about 0-3 gram into a weighed porcelain crucible.
Cover with the lid and heat, at first gently, over a small flame.
When the first reaction is over, heat the crucible for a few
minutes to a dull red heat, and then allow it to cool in a desic-
cator. The silver salt will be completely decomposed and leave
a dull white residue of silver. The crucible is now weighed and
the weight of silver determined.

MOLECULAR WEIGHT OF ORGANIC ACIDS         45

11

FIG. 36.

;r
rf

FIG. 37.
46             - PRACTICAL ORGANIC  CHEMISTRY

If Wis the weight of salt, w the weight of silver, and ;/ the
basicity of the acid, the molecular weight of the silver salt is
determined4from the following- formula :—

The molecular weight of the acid is then obtained by deduct-
ing n atoms of silver and adding n atoms of hydrogen.

^Example— 0-3652 grm. silver benzoate gave 0*1720 grin.
silver.

108  X             - 108 + I = 122-2.

0'I72O

Calculated for C7H602 ; M = 122

Molecular Weight of Organic Bases
Determination by means of the Platinum Salt. —
The organic bases form, like ammonia, crystalline chloroplati-
nates with platinic chloride of the general formula B2H2,PtClfl.
By estimating the amount of platinum present in the salt, it is
possible to calculate the molecular weight of the platinum corn-
pound, and consequently that of the base.
Dissolve about i gram of an organic base (brucine, strych-
nine, guinine, &c.) in 10 c.c. of a mixture of equal volumes of
concentrated hydrochloric acid and water. To the clear hot
solution add excess of platinic chloride and let it cool. Yellow
microscopic crystals of the chloroplatinate of the base separate.
(If the chloroplatinate of the base is very soluble in water, such
as aniline, it must be washed with strong hydrochloric acid,
pressed on a porous plate and dried in a vacuum-desiccator over
solid caustic potash.)
Filter on the porcelain funnel with the pump and wash three
or four times with small quantities of cold water. Press the
precipitate down and dry on a porous plate in the vacuum -desic-
cator. When thoroughly dry, weigh out about 0-5 to i gram of
the compound into a porcelain or platinum crucible, and heat
gently with the lid on, and then more strongly until the organic
matter is completely burnt away. Cool the crucible in the desio
ea.or and weigh.
If

MOLECULAR WEIGHT OF ORGANIC BASES         47

The molecular weight of the salt is calculated from the weight
ixj of the platinum, and IV of the salt, according to the formula
(the atomic weight of platinum being 195) :—
Wx 195
w
To determine from this the weight of the base, it is necessary
to deduct from the molecular weight of the salt that of H2PtC)6,                    /-I
and as two molecules of  the  base are contained in the salt,                    * |,
the result is halved.                                                                                     «£ y
Example—07010 grm. of aniline chloroplatinate,                                      ^
(C6H5NH2)2H2PtCle,                                                  'ijji
gave 0*2303 grm. platinum.                                                                           J'J
O7oio_xj95 = 594.2.   M.W. of the salt.                                     t-j
°'2303
594^-_ 409-9 = 9ri ^                                              )f|4
2                                                                 v#
Calculated for C6H7N ; M = 93.                          "                    j/V
:;l*
Preparations                                                *T
General Remarks.—Carefully read through the method.
References to the process are given under each heading. Be
clear as to the objects of the various steps described and the
nature of the materials employed. It cannot be too strongly urged
that in all cases where any doubt exists as to the nature of an
operation, a preliminary trial should be made in a test-tube with a
small quantity of the substance. This is especially necessary in
crystallisation where the quantity and character of the solvent are
unknown. A vast amount of time and material is thereby saved.
A small stock of clean and dry test-tubes (5 x f and smaller sizes)
should always be at hand for this purpose ; also watch-glasses
for microscopic examination of solid substances.
The yield of either the crude or purified product should
always be ascertained, and the purity of the product determined
either by the boiling-point or melting-point. A small rough
balance with celluloid pans, for use on the bench, is indispensable.
Select vessels of a size appropriate to the quantities dealt
with. Never use beakers for boiling or evaporating liquids, but
flasks and basins. Use ordinary, carefully selected,'corks rather
PRACTICAL ORGANIC CHEMISTRY

than rubber stoppers (which are attacked by many organic
liquids), and soften them well before use. The reactions
described at the end of each preparation are to be done in test-
tubes, and should not be neglected.
Above all, work with suitable, compact and clean apparatus
on a clean bench. The best results are usually obtained when the
preparation is carried out with something of the care and
accuracy of a quantitative analysis.
Where the asterisk occurs, it signifies that the operation must
be conducted in the fume cupboard.
Whilst the preparation is in progress, utilise the spare minutes
in reading the notes in the Appendix.
To facilitate reference to general manipulative processes,
which are described as they occur in conjunction with different
preparations, the following table is added.
Solids.                                       Page.
Filtration       ...............    53
Filtration under reduced pressure ...        ...    43
Crystallisation          ...        ...        ...        ...    52
Fractional crystallisation•   ......        ...   122
Sublimation  ...        ...        ...        ...        ...  226
Determination of melting-point    ...        ...    72
Liquids.
Dehydration...         ............    56
Determination of boiling-point      ...      ....    58
Distillation under reduced pressure          ...    84
Distillation in steam            ...        ...        ...   107
Fractional distillation    "     ...        ...        ...   136
Determination of specific gravity......    56
Liquids and Solids.
Heating under pressure......        24, 78
Determination of rotatory power......116
Mechanical stirring.........       90, 147
Purification of Methylated Spirit and Spirits of Wine
Methylated spirit, or spirits of wine 60—70 " over-proof, " may
generally replace the more costly absolute alcohol as a solvent
after undergoing a process of purification. The methylated
spirit must be of the old kind, consisting of a mixture of 9 parts
spirit of wine and i part purified wood-spirit, without the
ETHYL ALCOHOL

•?a

49

addition of paraffin i.e., it should give a clear solution with
water. It is, however, preferable to use rectified spirits 60-70
over-proof which can be bought free of duty by teaching institu-
tions on application to the Inland Revenue Board.

Methylated spirit contains, in addition to ethyl and methyl
alcohols, water, fusel-oil, acetalde-
hyde, and acetone. It may be
freed from aldehyde by boiling
with 2—3 per cent, solid caustic
potash on the water-bath with an
upright condenser for one hour, or
if larger quantities are employed,
a tin bottle is preferable, which
is heated directly over a small
flame (see Fig. 38). It is then
distilled with the apparatus shown
in Fig. 39. The bottle is here
surmounted with a T-piece hold-
ing a thermometer. The distil-
lation is stopped when most of the
spirit has distilled and the ther-
mometer indicates 80°. A further
purification may be effected by
adding a little powdered perman-
ganate of potash and by a second
distillation, but this is rarely ne-
cessary. The same method of
purification may be applied to
over-proof spirit, which will hence-
forth be called spirit as distinguished from the purified product
or absolute alcohol.

Ethyl Alcohol, C2H5.OH

«

Commercial absolute alcohol may be used for the preparations
which follow. It is obtained by distilling crude spirits of wine
over quicklime, and usually contains about 0-5 per cent of
water.

Properties.—Pure ethyl alcohol boils at 78-3°, and has a
sp. gr. of 0793 at I5°- It mixes with water in all'proportions

COHEN'S ADV. p.o.c.                                              E

FIG. 38.

I



'"

a

f
50                 PRACTICAL ORGANIC CHEMISTRY

Reaction.—A delicate test for ethyl alcohol is the iodoforw
reaction. Pour a few drops of alcohol into a test-tube and add
about 5 c.c. of a solution of iodine in potassium iodide, and then
dilute caustic soda solution until the iodine colour vanishes.
Shake up and warm very gently to about 60°. If no turbidity
or precipitate appears at once, set the test-tube aside for a
time. Yellow crystals of iodoform will ultimately deposit, which
have a peculiar odour, and a characteristic star shape when
viewed under the microscope. The same reaction is given with

FIG. 39.
other substances, such as acetone, aldehyde, &c., but not with
methyl alcohol.
PREPARATION i.
Potassium Ethyl Sulphate, CsH6OtSO8.OK
Dabit Ann. Ckint. Phys. 1800, (i) 34, 300 ; Claesson, /. prakt.
Chem. 1879 (2) 19. 246.
70 grms. (87 c.c.) absolute alcohol.1
50    5,     (27 cc.) cone, sulphuric acid.
The alcohol is poured into a round flask (J litre) and the
•sulphuric acid is slowly added and well mixed by shaking. A
1 For the preparation of methyl potassium sulphate the same quantity of methyl
alcohol is used ; in other respects the two processes are identical. The yield is
45—50 grams.
POTASSIUM ETHYL SULPHATE

considerable amount of heat is developed in the process. The
flask is now fitted with a reflux condenser (see Fig. 40) placed
upon the water-bath and heated for 2—3 hours. The product
now contains in addition to ethyl hydrogen sulphate, free sul-
phuric acid and unchanged alcohol. The liquid on cooling is
poured into i litre of cold water m a large basin and well stirred.
It is neutralised by adding chalk ground into a thin paste with
water. This precipitates the free sulphuric acid as calcium sul-
phate and converts the ethyl hydrogen sulphate into the soluble

FIG. 40.
calcium salt. The mixture is heated and filtered through a
large porcelain funnel (see Fig. 36) at the filter-pump, and the
precipitate pressed well down. The clear filtrate is heated on
the water-bath and a solution of potassium carbonate (about 50
grams) is added in small quantities until the liquid is slightly
alkaline. To ensure complete precipitation a little of the clear
liquid should be tested with a solution of potassium carbonate
before proceeding.
The calcium salt is thereby converted into the soluble potas-
sium salt and calcium carbonate is precipitated. The latter is
removed by filtration, as before, and the filtrate concentrated on
the water-bath to a small volume until a drop of the liquid, re-
moved on the end of a glass rod, crystallises at once on cooling.
i                                          E  2
PRACTICAL ORGANIC CHEMISTRY

The potassium ethyl sulphate is filtered and washed with a
little spirit or methylated spirit.1
Crystallisation.—The substance should now be recrystal-
lised. The success of many operations in practical organic
chemistry depends upon skill in crystallisation. The first essen-
tial is to select a suitable solvent, that is, one which dissolves
much more of the substance at a high than at a low temperature.
To discover a suitable solvent a small quantity of the substance
(o* i gram is sufficient) is placed in a test-tube and a few drops
of the solvent poured in. The common solvents are water,
methyl and ethyl alcohol, ethyl acetate, acetic acid, acetone, benz-
ene (also toluene and xylene) nitrobenzene, petroleum spirit and
ligroin, chloroform and carbon tetrachloride. If the substance
dissolves on shaking without warming or does not visibly
diminish on boiling, it may be discarded as unsuitable. If it
dissolves on heating or boiling and crystallises on cooling in
considerable quantity, it may be employed. Sometimes solutions
can be supercooled. In such cases, rubbing the sides of the
test-tube with a glass rod will cause the substance to deposit. A
convenient method of crystallisation may be occasionally em-
ployed by using two miscible solvents in one of which the
substance is soluble and in the other insoluble. The substance
is then dissolved in a small quantity of the first solvent and
the second added gradually until a turbidity appears. Alcohol
and water, and benzene and petroleum spirit are often used in
conjunction in this way. If a substance of low melting-point is
to be crystallised care should be taken that sufficient solvent
is present to prevent the substance separating at a temperature
at which it is still liquid. The interval of temperature may be
increased after the solution has reached the ordinary tempera-
ture, by cooling it in a freezing mixture, when some of the
solid will be deposited.
In the present instance spirit or methylated spirit (purified)
will be found an efficient solvent for potassium ethyl sulphate.
The following is the mode of procedure when a volatile or in-
flammable solvent is used : the substance is placed in a round
flask attached to an upright condenser and heated on the water-
bath. The form of apparatus is that already described (see Fig.
1 If methylated spirit is used it must be purified according to the method described
on p. 48
POTASSIUM ETHYL SULPHATE

53

4,0-) Small quantities of spirit are added and kept boiling until
£t solution is obtained. A small quantity of impurity may remain
^ndissolved. The hot solution is at once decanted or filtered

d.

FIG. 41.

tlirough a fluted filter (Fig. 41)  or hot water funnel (Fig. 4-)
irxto a beaker and allowed to cool.

A flitted filter is made by first folding a large circular filter
paper in the ordinary way. It is then half opened out and the
t\vo quadrants folded towards the middle line (see a, Fig. 41),
This makes three creases with the hollows on the same side.
IT he filter is now turned over and each section folded down the

FIG. 42.

centre so that the hollows of the four new creases alternate
Avith the ridges of the three others as shown at b. The paper
w-lien opened now appears like c. The two rectangular flutings
Indicated by an asterisk have still to be divided by a crease
54                PRACTICAL ORGANIC CHEMISTRY
down the middle. The filter is now pushed well into the
funnel, the stem of which is cut off short as shown at d.
A hot-water funnel is shown in Fig. 42. It consists of a
jacketed metal funnel, with a projecting metal tube. The vessel
is partly filled with water which is boiled by placing a small
burner under the end of the tube. The glass funnel is placed,
within the metal-jacket. By keeping the liquid hot, crystallisation
in the filter is thus prevented.
Before filtering an inflammable liquid such as alcohol the flame
must be removed. The potassium ethyl sulphate is dried on a
plate of unglazed earthenware or on a thin pad consisting of
three or four sheets of filter paper, with another sheet over the
crystals to keep out the dust. On concentrating the mother
liquors on the water-bath, a further quantity of crystals may be
obtained. Yield 35—40 grams. The following equations
express the chemical reactions which occur:
1.               c2rrson + H2so4 = c2n5so4H + H2o
Ethyl hydrogen sulphate.
2.       2C2H5S04II + CaC03 = (C.2H5S04),Ca + HSO + C02
Calcium ethyl sulphate.
3.          (CoH5S04\jCa + KX03 = 2C,tt£O4K + CaCO3.
Potassium ethyl sulphate.
Properties. Colourless, foliated crystals ; easily soluble in
water and dilute alcohol, less soluble in. absolute alcohol.
Reactions. I. Dissolve a little of the recrystallised salt in water,
and add barium chloride solution. There is no precipitate, as
the barium salt of ethyl hydrogen sulphate is soluble in water.
2. Boil a little of the solution of the salt with a few drops
of dilute hydrochloric acid for a minute and add barium chloride.
A precipitate of barium sulphate is formed, as, on boiling ethyl
hydrogen sulphate in aqueous solution, it is decomposed into
sulphuric acid and alcohol (see Appendix, p. 234).
PREPARATION 2.
Ethyl Bromide (Monobromethane), C2H5Br.
De Vrij, Jahresber^ 1857, 441.
100 grms. potassium bromide,
loo    j,     (54 c.c.) cone, sulphuric, acid.
60   3,     (75 c.c). absolute alcohol
ETHYL BROMIDE

55

Fit up the. apparatus as shown in Fig. 43. The distilling
flask should have a capacity of not less than i litre, and is
attached to a long condenser. An adapter is fixed to the end~of
the condenser, dipping into a conical flask (250 c.c.)3 which
serves as receiver. The alcohol and sulphuric acid are mixed
in the distilling flask and cooled to the ordinary temperature
under the tap. The potassium bromide, coarsely powdered, is
then added. The flask, which is closed with a cork, is fixed to
the condenser and heated on the sand-bath. A sufficient quan-
tity of water is poured into the receiver to close the end of the
adapter. After a short time the liquid in the flask begins to
boil and froth up, and the ethyl bromide, in the form of heavy

FIG. 43.
drops of colourless liquid, distils and collects at the bottom of
the receiver. If the liquid threatens to froth over, the flask must
be raised from the sand-bath for a moment. The distillation is
continued until no further drops of oil appear at the end of
the condenser. As the ethyl bromide has a low boiling point
(38-39°), it is desirable to surround the receiver with ice during
this operation. The distillate is now removed and poured into
a separating funnel (Fig. 44), and the lower layer of ethyl bro-
mide separated. The water is thrown away and the ethyl
bromide poured back together with about an equal bulk of dilute
sodium carbonate solution and shaken up. The ethyl bromide
is withdrawn, as before, and again shaken up with water.
Finally, it is carefully separated from the water and run into a
dry distilling flask. The small quantity of water which remains,
PRACTICAL ORGANIC CHEMISTRY

and renders the liquid turbid, is removed by adding a dehydrat-

ing agent.

Dehydration. Moisture can be readily removed from liquids
by adding a solid hygroscopic substance which does not act
chemically upon the liquid. The common
dehydrating agents are calcium chloride,
potassium carbonate, sodium sulphate
(anhydrous), quicklime, &c. Alkalis can-
not "of course be used for dehydrating or-
ganic acids, nor can calcium chloride be
employed in conjunction with alcohols or
organic bases, with which it combines. In
the present instance it can be used. A few
small pieces of the granulated or fused.
calcium chloride are added to the liquid.
The flask is corked and left to stand for
some hours until the .liquid becomes
clear. It is then distilled. A ther-
mometer is inserted into the neck of
the flask with the bulb just below the
side tube. The flask is attached to a con-
denser and heated gently on the water-
bath, so that the liquid distils at a moderate speed (2 — 3 drops
a second). The temperature is noted and the portion boiling at
35™43° collected in a separate flask. This consists of ethyl
bromide which may contain a little ether. Yield 75 — 80 grams.

FIG. 44.

C2H5OH

Alcohol.

H2S04 = C2H6.H.S04 + H3O.

~              Ethyl hydrogen sulphate.

C2H5.H.S04 4- KBr == C2H,Br + KHSO4.
Ethyl bromide,         ,
Properties— Colourless liquid ; b. p. 38 '8° ; sp. gr. 1*47 at 15^
(see Appendix, p. 234).
Determination of Specific Gravity.— A simple method
for determining the specific gravity of liquids is as follows: A
pyknometer, or small glass bottle, is used of about 20 to 30 c.c.
capacity, with narrow neck, upon which a mark, is etched and
which is closed by a ground glass stopper (Fig. 45).
The bottle is thoroughly cleaned and dried by warming and
aspirating air through it, after which it is allowed to cool and
weighed. It is then filled with the liquid, which is poured in
ETHYL BROMIDE                                57

through a funnel, the stem of which is drawn out so as to pass
through the narrow neck. The bottle is placed in a mixture of *
snow or pounded ice and left a quarter to half an
hour, until the contents have a temperature of o°.
The meniscus is now adjusted until it coincides
with the mark on the neck of the bottle. If
more liquid has to be added, this may be
done from a small pipette with capillary de-                     ^

livery tube ; if some of the  liquid has to be                     I  ,*'

removed, a thin   roll  of filter  paper   may be                     \   f

inserted   which will absorb it.    The   bottle  is
then stoppered,dried on the outside, left in the                    . l|*

balance case  for  a  quarter of an  hour,  and                    J

weighed.    It   is   then   emptied,   cleaned,  and                     ' (   |

dried, and filled with distilled water previously                       i

boiled.    The water is cooled to o°, the meniscus                     <' V

adjusted   and   the   bottle   weighed, the   same
IG 45'        process being repeated as that just described.                        -*

The following expression will  give the specific gravity of the                     .    '

liquid at o° compared with water at o° :—                                                       . jf

Where iu± — weight of empty bottle,
w.2 =        „         bottle,and water at o°,
7e/3 =        „         bottle and liquid at o°;
or, if compared with water at 4°, the above number must be
multiplied by the density at o° = 0*999873.
A very delicate and useful piece of apparatus, which is
readily made with the blow-pipe, is Perkins5 modification of
Sprengel's pyknometer.1 It is especially adapted for small quan-
tities of liquid and for the more volatile ones. The apparatus
(Fig. 46) consists of a U~tuDe to hold from 2 to 10 c.c., drawn
out at each end into a fine capillary. The one capillary limb, #, is
bent outwards and is furnished with a small bulb ; the other, £,
is bent at a right angle with the first. On the limb <z, between
the bulb and the top of the U-tube a mark is etched. The
1 Trans. Chem. Soc. 1884, 45, 421.
PRACTICAL ORGANIC CHEMISTRY

tube is dried and weighed, and the liquid drawn in through the
limb b, until it half fills the small bulb on the limb a. The
apparatus is cooled in ice and water, and the meniscus adjusted
to the mark on a by tilting the tube until the limb b has a hori-
zontal position. To the end of this limb a piece of filter paper
is applied, until the liquid sinks to the desired position in the

FiG 46.
limb a. The (J-tube is then brought to the vertical position,
loose glass caps placed over the ends of the two limbs, the
apparatus carefully dried, and allowed to stand and weighed.
The operation is then repeated with distilled water.
Example—An experiment with ethyl bromide gave the fol-
lowing result:—
Weight of tube empty .   .   .......6-242 grams
+ ethyl bromide at o°  .   . 9^472      „
+ water at o°......8*4*7      »
A J =0-999873 *%ZjL= 1-485-
Determination of"the Boiling-point.—A correct deter-
mination of the boiling-point of a liquid is made with a standard
ETHER

59

thermometer, z>.,ione that has been calibrated, and the o° ancl IOOQ
points carefully determined. An ordinary thermometer corrected
by a standard thermometer at Kew will serve equally well.
Correction must also be made for barometic pressure. This is
approximately 0-043° for every I mm. below 76o-(Landolt). A
further correction is required for the thread of mercury, which
may project above the vessel. For this correction the following-
formula may be used :—

N(T-/)o*oooi54.

Where T = apparent temperature in degrees.

/ = temperature of a second thermometer, the bulb
of which is placed at half the length N above
the vessel.
N = length of the mercury column in degrees from

above the vessel to T.
0*000154 = apparent expansion of mercury in glass.

This correction may be avoided by using short (Anschiitz)
thermometers, in which the mercury thread is entirely immersed
in the vapour. A rough correction for points above 100° may
be made by determining the boiling points of pure organic
substances, such as naphthalene, 2i6'6°, &c.

m

••I

A

'•<!•

ijfj.ii

PREPARATION 3.
Ether (Diethyl Ether, Diethyl Oxide), (C2H5).2O
V. Cordus (1544); Jottrn. Pharm^ 1815, 1, 97 ; Williamson,
Phil Mag. 1850, (3)37, 35°.
150 grms. (80 c.c.) cone, sulphuric acid.
85    „     (no c.c.) absolute alcohol.
A distilling flask (\ litre) is fitted with a double-bored cork.
Through one hole a thermometer is inserted, the bulb of which
must be covered by the liquid in the flask and through the
other a tap-funnel passes. The side-tube of the distilling flask
is fixed by a cork into the upper end of a long condenser. An
adapter is fitted to the lower end and passes through the neck
of a flask, which is surrounded by ice. The apparatus is shown
6o

PRACTICAL ORGANIC CHEMISTRY

in Fig. 47. The sulphuric acid and alcohol are cautiously
mixed together in the distilling flask, which is then placed upon
a sand-bath and attached to the condenser. The mixture is
heated to 140° and alcohol is run in from the tap-funnel at the
same speed as the liquid distils (about three drops a second).
The temperature must be kept constant at 140—145°. When
about twice the quantity of alcohol contained in the original
mixture has been added and converted into ether, the distillation
is stopped. The receiver now contains, in addition to ether,
alcohol, water and sulphurous acid, The liquid is poured into

FIG. 47-
a large separating funnel and a small quantity (30—40 c.c.) of
dilute caustic soda added and well shaken. After settling,
the caustic soda solution is drawn off below, and about the
same quantity of a strong solution of common salt added,
and the process of shaking and drawing off repeated. The
ether, which is now free from sulphurous acid and from
most of the alcohol, still contains water. It is therefore
poured into a large dry distilling flask and some pieces
of solid calcium chloride added. It is allowed to stand
loosely corked overnight. The distilling flask is now attached
to a long condenser and heated on the water-bath. The
ether, which distils, still contains traces of alcohol and water,
which it obstinately retains and from which it can only be freed
ETHER

61

by a further treatment with metallic sodium. A few very thin
slices of sodium are dropped into the receiver and the vessel
closed with a cork, through which an open calcium chloride tube
is inserted to allow any hydrogen to escape and to prevent the
entrance of moisture.

When the sodium produces no further action, the ether is
decanted from the sodium residues into a distilling flask and
distilled on the water-bath. A thermometer is placed in the
neck of the flask to indicate the boiling-point, which should be
constant at 35°.

C2H5OH -1- H,S04 = C9H5S04H + H.,0.
C2H6S04H + C2H6OH - C2H5.O.C2H5 +-H2SO4.

Properties.—Colourless, mobile liquid ; b.p. 35° ; sp. gr. 0720
at 15° ; burns with a luminous flame ; not miscible with water ;
9 parts of water dissolve i part of ether, and 35 parts of ether
dissolve i part of water at the ordinary temperature. See
Appendix, p. 236.

Commercial Ether is made from methylated spirit and
contains alcohol, water, and other impurities, and for many

FIG. 49.

reactions requires to be purified. The following method of purifi-
cation may be employed. The ether is distilled over a little
coarsely powdered caustic potash, then placed in contact with solid
calcium chloride for several hours, and finally decanted and
treated with metallic sodium. It is convenient to use a sodium
knife (Fig. 48) or press (Fig. 49) for preparing the^ sodium.
In the former the metal can be cut into very thin slices, and
in the latter it is pressed into fine wire through a circular steel die,

'**,;
62                PRACTICAL ORGANIC CHEMISTRY

It must be remembered that ether is highly inflammable, and
also exceedingly volatile, and great care should be taken that
no flame is in the neighbourhood of the liquid. It must on no
account be distilled over the bare flame, but always from the
water-bath, and then with a long well-cooled condenser. The
distillation of large quantities should be avoided as far as
possible. In such cases it is convenient to employ a distilling
flask of moderate size (250 c.c.), and to add, as the liquid distils,
a fresh supply of ether or ethereal liquid from a tap-funnel
inserted through the neck of the flask, which can be done
without interrupting the distillation.
PREPARATION 4.
Bthylene Bromide.   CH2Br. CH2Br.
Balard, Ann. Chim. Phys. 1826 (2), 32, 375 ; Erlenmeyer.
Bunte, Annalen, 1873, 168, 64.
25 grms. (30 c.c.) absolute alcohol.
150    „    (So c.c.) cone, sulphuric acid.
200    „     (65 c.c.) bromine (which must be measured
out in the fume-cupboard).
300 „ of a mixture of 100 grms. (124 c.c.) alcohol
and 200 grms. (108 c.c.) cone, sulphuric
acid.
Fit up an apparatus as shown in Fig. 50. It consists of a
round flask (2 litres), which is furnished with a double-bored
cork. A tap-funnel is inserted through one hole and a delivery
tube through the other, by which it is connected with two
wash-bottles with safety tubes. A useful form of wash-bottle is
that shown'in Fig. 50 and in section at a. Otherwise a three-
necked Woulff bottle will serve, with a long tube inserted through
the central neck. The wash-bottles are one-third filled with
caustic soda solution. The two ordinary wash-bottles standing
in the trough of water contain the bromine. The first contains
about 50 c.c. of bromine and i c.c. of water and the second about
15 c.c. of bromine and i c.c. of water. The latter is attached to
a wide U tube or cylinder containing pieces of soda-lime. If a
cylinder is used a layer of glass fragments or marbles should
ETHYLENE BROMIDE

form a layer round the orifice of the inlet tube with the soda-
lime above.

The joints being tight, the mixture of 25 grams of alcohol and
i 50 grams of sulphuric acid is run into the large flask containing
a little dry sand and heated with a small flame on the sand-bath
until a steady stream of gas is evolved. When this occurs the
mixture of alcohol and sulphuric acid is dropped in slowly from
the tap-funnel. It is important to moderate the temperature
to prevent excessive frothing and the separation of carbon,
which, however, cannot altogether be avoided. A considerable
quantity of sulphur dioxide which is evolved with the ethylene

FIG. 50.
is removed by the caustic soda in the wash-bottles. If the
water surrounding the bromine bottles becomes warm, small
lumps of ice should be thrown in. The caustic soda should
be occasionally renewed, otherwise sulphur dioxide may pass
into the bromine and reduce it to hydrobromic acid. If the
pressure in the apparatus causes a back rush of bubbles
through the tap-funnel attached to the flask, the difficulty is
met by inserting the stopper in the tap-funnel. After a
few hours the bromine in both vessels is decolourised or at
least changes to a straw colour. The crude ethylene bromide
is removed and shaken with dilute caustic soda solution, then
with water, separated from the aqueous layer and dehydrated
64               PRACTICAL  ORGANIC  CHEMISTRY

over small pieces of calcium chloride. It is decanted or
filtered from the calcium chloride and distilled. The distillate is
collected at 130 — 132°. The yield is nearly equal to the
weight of bromine taken.

Properties. — Colourless liquid, which solidifies, at o° to a
crystalline mass and melts at 9° ; b.p. 131'S0 ; sp.gr. 2*19 at if.

Reaction.— Attach a 100 c.c. flask to a short upright con-
denser (see Fig. 86) and to the upper end of the condenser
attach a vertical delivery tube, dipping into an ammoniacal
cuprous chloride1 solution. Pour i — 3 c.c. of ethylene bromide
into the flask with 4 times its volume of strong methyl alcoholic
potash, which is prepared by boiling methyl alcohol with excess
of caustic potash on the water-bath with upright condenser. On
gently heating, a rapid evolution of acetylene occurs and the
characteristic brown copper compound (C2H2Cua,H2O) is pre-
cipitated from the cuprous chloride solution.

Acetyene.

See Appendix, p. 237.

PREPARATION 5.

Acetaldehyde, CH3.CO.H

Liebig, Annalen^ 1835, 14, 133 ; Staedeler, /. prakt. Cheni.,
1859, (076, 54-

100 grms. potassium bichromate
420 c.c. water.

A mixture  of 100 grms.   (125   c.c.)   absolute   alcohol
and 140 grms. (75 c.c.) cone, sulphuric acid.

100  c.c.  methylated   ether,   which   has   been   left   to
stand  over solid  caustic potash  for a few  hours,  and
then distilled off from the water-bath.
A round flask (i-| litre) is provided with a double-bored cork.

washed once or twice by decantation and dissolved in a strong solution of ammonium
chloride. When required a little ammonia is added sufficient to give a clear blue
solution.
ACETALDEHYDE

A^bent tube, which passes through one hole, connects the flask
with a condenser and receiver. A tap-funnel is inserted through
the other hole. The flask is placed upon a sand-bath, and the
receiver is cooled in ice. It is important that all the corks
should be tight, as a small leak will considerably diminish the
yield. The potassium bichromate in small pieces and the
420 c.c. of water are placed in the flask and gently warmed.
The flame is then removed, and the mixture of alcohol and

FIG. 51.

sulphuric acid, which may be used warm, is slowly added from
the tap-funnel. The flask is occasionally shaken. A consider-
able rise of temperature occurs and the liquid darkens, whilst
aldehyde, with a little water and alcohol, distils. When the
mixture has all been added, the flask is heated on the sand-bath
until all the aldehyde has distilled (about 150 c.c.), which may
be determined by removing the cork from the flask and noticing
if the smell of aldehyde is still perceptible. The distillate is now
redistilled on the water-bath in the apparatus shown in Fig. 51.
COHEN'S ADV. P. o. c.                                                F

ilf
66

PRACTICAL  ORGANIC  CHEMISTRY

The flask is attached to an upright condenser in which the
water is kept at a temperature of 30 — 35°. Alcohol and aqueous
vapour condense in the condenser ; the aldehyde, on the other
hand, passes by a tube attached to a 100 c.c. pipette into two
narrow (TOO c.c.) cylinders, one-third filled with the dry ether,
and cooled in ice-water. The aldehyde readily dissolves in the
ether and is rapidly absorbed. If the ethereal solution is now
saturated with dry ammonia gas, the whole of the aldehyde
separates out in the form of colour-
less crystals of aldehyde-ammonia,
CH3.CH.OH.NH2. The apparatus
for preparing the dry ammonia is
shown in Fig. 52. The flask contain-
ing strong ammonia solution is heated
by a small flame, when the gas is
readily evolved and passes up the
tower, which is filled with soda-lime
or quicklime. The ethereal solution
is saturated with the gas, and is then
allowed to stand for an hour.

The ether is then decanted from
the crystals, which are drained at
the filter-pump, washed with a little ether, and finally dried in
the air on filter-paper. Yield of aldehyde-ammonia, 25 — 30
grams. It may be used for the reactions described on p. 67.

Pure aldehyde may be prepared from the aldehyde-ammonia
as follows : The crystals are dissolved in an equal weight
of water and distilled on the water-bath with a mixture
of ij parts of concentrated sulphuric acid and 2 parts of water,
the receiver being well cooled in ice. The temperature of the
water-bath is gradually raised until the water begins to boil,,
and the distillation is then interrupted. The distillate is de-
hydrated over an equal bulk of calcium chloride, from which it
is distilled in the water-bath, heated to 30°. The anhydrous
aldehyde is kept in a well- stoppered bottle.

FIG,  52.

3C2H6(OH) + K2Cr207 + 4H9SO4 = 3C,H4O

Cr,(S04)3 + ;H,0
C2H40 + NH, = CH,CH.OH,NH
2CH8CH.OH.NH2 + H2S04 = 2CH3.CO.H +

K0SO
METHYL ALCOHOL                            67
Properties.—Colourless liquid with a distinctive smell; b.p.
21° ; sp. gr. 0*807 at o° ; soluble in water, alcohol and ether.
Reactions.—Acetaldehyde and many of the aliphatic aldehydes
are characterised by the following reactions :—
1.  Prepare a little ammonio-silver nitrate by adding dilute
ammonia drop by drop to silver nitrate solution • until the pre-
cipitate just dissolves.   Add to a third of a test-tube full of the
ammonia-silver nitrate solution about i c.c. of aldehyde,, and
place it in a beaker of hot water.   A mirror of metallic silver is
deposited.    Ag2O + C2H4O = Ag2 + C2H4O2 (acetic acid).
2.  To i c.c. of aldehyde add 2-3 times its volume of a cold
saturated solution of sodium bisulphite and shake up.     The
additive compound,   CH3CH.OH.SO3Na, crystallises  out   on
standing.   A crystal of the substance introduced into the liquid
will hasten its formation.    The bisulphite solution is prepared
either by dissolving sodium metabisulphite   in water, or by
passing sulphur dioxide into soda crystals covered with a layer
of water.    It forms an apple-green solution, smelling strongly
of sulphur dioxide. The sulphur dioxide is conveniently obtained
from a bottle of the liquid which can be purchased, or by dropping
concentrated sulphuric acid on to solid sodium sulphite.
3.  A solution of magenta decolourised by  sulphur  dioxide
becomes violet on the addition of a drop of aldehyde (Schiff;.
Prepare a weak solution of magenta by dissolving a crystal in
half a test-tube of water and bubbling in sulphur dioxide until
the colour disappears.    Now add a few drops of aldehyde.
4.  Boil a few drops  of aldehyde  with i—2 c.c. of caustic
potash   solution.    The   liquid  becomes   yellow and  a  brown
resinous precipitate is formed.
5.  Add a drop or two of concentrated sulphuric acid to I c.c.
of aldehyde.    The mixture becomes hot in consequence of the
aldehyde undergoing polymerisation to paraldehyde (C2H4O)3j
b.p.   124°, which separates as an oil  on adding water.     See
Appendix', p. 238.
Methyl Alcohol.    CH3.OH
Commercial methyl alcohol is obtained by purifying wood spirit.
It often contains a little acetone, which may be detected by the
iodoform reaction (see p. 50). It may, if necessary, be purified by
boiling it, using an upright condenser, with 3—4 per cent, of solid
68                PRACTICAL ORGANIC CHEMISTRY

caustic potash on the water-bath, and then distilling. It is
freed from water by standing for twenty-four hours in a flask
one-third filled with freshly-burnt quicklime, and re-distilling
from the water-bath, using a thermometer.

Properties. — Colourless liquid ; b. p. 66—67°';  sp. gr. 0796
at 20°.

PREPARATION 6.

Methyl Iodide (lodomethane), CH3I
Dumas and Peligot, Annalen, 1835, 15, 20.

1 8 grins, methyl alcohol.
5     „    red phosphorus
50     „     iodine

Attach a flask (250 c.c.) to an upright condenser, and bring
into it the methyl alcohol and red phosphorus. Add the iodine
gradually by detaching the flask for a moment from the con-
denser. A considerable evolution of heat occurs. When the
iodine has'been added the flask is left attached to the condenser
over night, and the contents then distilled from the water-bath
using a similar apparatus to that of Fig\ 43, p. 53. The dis-
tillate is shaken up with dilute caustic soda in a separating
funnel, to remove iodine and hydriodic acid. If sufficient
caustic soda has been used the lower layer of methyl iodide will
be colourless. Separate -the methyl iodide, add a few. pieces of
solid calcium chloride, and after standing until clear, distil from .
the water-bath with thermometer. Yield 45 grams. Ethyl
iodide and the other alkyl iodides are prepared in precisely the
same fashion.

Properties. — Colourless, highly refractive liquid ; b. p. 45° ;
sp:gr. 2-27 at 15°.
Reaction. — Shake a few drops of methyl iodide with an
alcoholic solution of silver nitrate. A white precipitate of a
compound of silver iodide and silver nitrate is deposited, which is
decomposed and gives yellow silver iodide on adding water.
See Appendix^ p. 240.
AMYL ALCOHOL                               69

Amyl Alcohol, C5Hn.OH.

Commercial amyl alcohol is contained in fusel oil from fer
mentation and consists mainly of isobutyl carbinol together
with about 13 per cent, of secondary butyl carbinol, which
renders the liquid optically active. It turns the plane of polar-
isation to the left (see p. 116).

Properties. — Colourless, highly refractive liquid with a burning
taste and penetrating smell ; b. p. 131 — 132° sp. egr., o'8ii3 at
19° ; dissolves in 39 parts of water at 16*5°.

PREPARATION 7.
Amyl Nitrite,. C6HUO.NO.

Balard ; Guthrie, Quart. J. C. S.^ 1858, 11, 245 ; Rennard,
Jahresb., 1874, P- 352-

30 grms. (37 c.c.) amyl alcohol.

30     „     sodium nitrite (finely powdered).

1 8     „     ( 10 c.c.) cone, sulphuric acid.

The amyl alcohol and sodium nitrite are mixed in a flask
(500 c.c.), and whilst the' mixture is cooled in ice-water, the
cone, sulphuric acid is added drop by drop from a funnel with
constant shaking. Towards the end of the process a. more
vigorous reaction sets' in, when care must be taken to add the
sulphuric acid more slowly. When the whole of the acid has
been added, the top layer of amyl nitrite is decanted into a
separating-funnel. A little water is then added to the residue
and, after shaking, a further quantity of amyl nitrite separates
and is decanted as before. The whole of the amyl nitrite
is then separated from water, dehydrated over calcium chloride
and distilled. The liquid boiling at 95 — 100° is collected
separately. Yield, 30 — 35 grams.

Properties. — Yellow-green liquid with a peculiar penetrating
and sweet smell, which, on inhaling, causes a rush of blood to
the head \ b. p. 96° ; sp. gr. 0*902. See Appendix, p. 240.
Acetone (Dimethyl ketone), CH3.CO.CH3.
Commercial acetone is obtained from  the products of the
distillation of wood.    To purify it, it is shaken with a saturated
70

PRACTICAL ORGANIC CHEMISTRY

solution of sodium bisulphite (see Reaction 2, p. 67). The crystal-
line mass, C3H6ONaHS03, is filtered and well drained and then
distilled with sodium carbonate solution. The distillate is
dehydrated over solid calcium chloride and finally distilled.

Properties.—Colourless liquid with a pleasant colour ; b. p.
56*3° ; sp. gr. 0792 at 15° ; soluble in water.

Reactions.—I. Acetone gives the iodoform reaction like ethyl
alcohol5 (p. 50). 2. Dissolve a few crystals of /-bromophenyl-
hydrazine or /-nitrophenylhydrazine in a few drops of glacial
acetic acid, dilute with about i c.c. of water and add a drop of
acetone. The bromo- or nitro-phenylhydrazone of acetone
separate as crystalline precipitates.

•'

PREPARATION 8.
Chloroform (Trichloromethane), CHC13.
Liebig, Pogg. Ann.) 1831, 23, 444 ; Dumas, Ann. Chim. Phys.^
1834,56,115-                                                                                .*
200 grms. bleaching powder (fresh).
800 c.c. water.
40 grms. (50 c.c.) acetone.
A large round flask (4 litres) is fitted with a cork, through    .
which a bent tube passes connecting the flask with a long con-
denser and receiver.    The flask is placed upon a large sand-
bath.    Grind the bleaching powder into a paste with 400 c.c. of
water and rinse it into the flask with the remaining 400 c.c.
Add the acetone and attach the flask to the condenser.    Heat
cautiously until the reaction sets in, which is indicated by the      ^
frothing of the liquid.    Remove the flame for a time, and when
the reaction has moderated, boil the contents until no more
chloroform distils.    This is easily determined by collecting the
distillate in a test-tube and observing if any drops of heavy      j
liquid are present.   The distillate is shaken with dilute caustic
soda solution in a separating funnel and the lower layer of
chloroform run into a "distilling flask.    A. few pieces of solid
calcium chloride are added and left until the liquid is clear,
when it is distilled from the water-bath with a thermometer    >,
inserted into the neck of the flask.    Yield about 40 grams.
ACETOXIME

71

The bleaching powder acts as though it consisted of a
compound of calcium hydrate and chlorine, and the process
probably occurs in two stages.

Trichloracetone is first formed, which is then decomposed by
the lime into calcium acetate and chloroform. .
Properties. — Colourless liquid possessing a sweet smell, b. p.
60—62°; sp.gr. 1-498 at 15°; very slightly soluble in water;
non-inflammable. As chloroform slowly decomposes in presence
of air and sunlight into phosgene, it is usual to add a little
alcohol to the commercial product, which arrests the change.
Pure chloroform is neutral to litmus, has no action on silver
nitrate solution and does not discolour concentrated sulphuric
acid when shaken with it for an hour or left for a day.
Reactions. — I. Heat a few drops with double its volume of
methyl alcoholic potash. On the addition of water a1 clear
solution is obtained. Potassium formate and chloride are
formed. CHC1S+4KOH = 3KC1 + HCO.OK + 2H2O.
2. Bring into a test-tube two drops of chloroform, one drop of
aniline and i c.c. of alcoholic potash and warm in the fume
'cupboard. Note the intolerable smell of phenyl carbamine
(carbatnine reaction), CHC13 + C0H5NH2 + 3KOH=C6H6NC +
3KCl + 3H2O. Wash out the contents of the test-tube in the
fume cupboard.
PREPARATION 9.
CH3
I
Acetoxime, C:NOH
I
CHo
V. Meyer, Fanin, Ber., 1882, 15, 1324.
5  grms. hyclroxylamine hydro chloride in 10 c.c. water
3     „    caustic soda in 10 c.c. water
6     ,,    (7*6 c.c.) pure acetone.
Add the acetone to the mixture of the hydroxylamine
hydrochloride and caustic soda in a small flask. The flask is
then corked and left for twenty-four hours, during which the
I

'                            72                PRACTICAL ORGANIC CHEMISTRY

I                           crystalline oxime separates.    The presence of any free hydroxyl-

\                         amine is then tested in a few drops of the liquid with Fehling's

solution, or by merely adding a drop or two of copper sulphate,
r                          then a sufficient quantity of caustic soda to produce a clear blue

solution and warming.   An orange-red precipitate of cuprous
! |                         oxide   indicates   uncombined   hydroxylamine.      If   no    free

hydroxylamine is present, the liquid is shaken up with an equal
•*i                         volume of ether,   in   which   the   acetoxime   dissolves.     The

«                           ethereal solution is separated and the process repeated twice

1                         with fresh ether.     The united ethereal extract  is  filtered,   if

j                        necessary, through a dry filter into a distilling   flask.    The

|                        greater part of the ether is distilled off on the water-bath.    The

!                        remaining liquid is poured into a glass basin and the rest of the

ether left to evaporate in the air, the last traces being removed
by heating for a few minutes on the water-bath.    The acetoxime
i<*                         separates out on cooling in colourless needles.     It is dried ori

I                        a porous plate and recrystallised from a little petroleum spirit

' ||                        m. p. 61—62.°   Yield 4—5 grams.

,1                                     CH3. CO.CH3 + NH2OH.HC1 4- NaOH

fl                                                   =CH3.C:NOH.CH3 + NaCl + 2H2O

i!                           Properties.—Colourless needles ; m. p. 60°.

fj                           Reaction.—Boil a small quantity for a few minutes with dilute

hydrochloric acid, and test with Fehling's solution. The oxime
is decomposed into acetone and hydroxylamine,

CH3.C(NOH).CH3+ H2O = CH3.CO.CH3 + NH3OH.
Melting-point Determination.—For this purpose the
following apparatus is used (Fig. 53).   A small sample of finely
powdered substance, which has been carefully dried, is introduced
into a capillary tube of about i mm. inside diameter sealed at
|§                   one end.    The tube is made from soft thin-walled glass tubing,

about 15 mm. diameter, by rotating it in the blow-pipe flame until
,   the glass softens, and then quickly drawing it out.     The long
I "'^ i                         capillary is then broken into lengths of about 7 cm. (2^ in.) by

§ j      , '                    scratching across with a writing diamond, and each short tube

is sealed at one end. To introduce the substance, it is con-
venient to scoop up the finely powdered material off a watch
glass with the open end. By tapping the closed end on
the bench, the powder is shaken down. The quantity intro-
duced should occupy a length of about 2—3 mm. when tightly

i
MKLTING.POINT DKTKKM INATK >N

73

packed. The tube is attached to a thermometer (preferably with
a very small bulb) so that the substance is level with the bulb. The
attachment may be made by a narrow rubber rintf or by simply
moistening the side* of the capillary with the thermometer bulb,
which has been dipped in the liquid in the bath, and then
pressing it against the thermometer stem. The thermometer
passes through a cork inserted into a round flask with a Ionj»'
neck, the bull* of which is throe-quarters filled with concentrated
sulphuric: acid, }*lyi:erol, ur castor oil. The ik»bk is clumped to a

retort stand and is heated very gradually by a small flame. In-
stead oi «lamping the flask to a rclort stand* it <"an be fixed in a
small brass tripod, shown in Kig. 53, which fits on to an ordinary
laboratory tripod and from which it can be removed when not
required,1 When a certain temperature is reached the substance,
if pure, melts suddenly within-one or two degrees. When
approaching the melting-point, it is desirable to remove the
flame or turn if very low so that the rise of temperature is very
gradual If the liquefaction is protracted, it is an indication
that the substance is not pure. The melting-point, obtained in
this way, lu be quite accurate, must be corrected for the

l :.i.uit!)c;un hr pun

| from Mr, J.

mt !*hv'»ic?*
74                PRACTICAL ORGANIC CHEMISTRY

temperature of the thread of mercury outside the liquid, the
same formula being used as in the correction for the boiling-
point (see p. 58). When the acid becomes discoloured, a crystal
of potassium nitrate will remove the colour on warming.
Acetic Acid, CH3.CO.OH.
Commercial acetic acid is manufactured from pyroligneous
acid obtained in the destructive distillation of wood. The latter
is neutralised with lime, and separated by distillation from wood-
spirit and acetone. The crude calcium acetate, which has a
dark colour, is then distilled with the requisite quantity of con-
centrated hydrochloric acid. Anhydrous or glacial acetic acid
is obtained by distilling fused sodium acetate with concentrated
sulphuric acid.
Properties.—Colourless liquid with pungent smell ; b. p.
119°; m. p. 167°; sp. gr. 1*055 at 15°. It should not decolorise
a solution of permanganate. The vapour of the boiling acid is
inflammable.
Reactions.—Add a few drops of alcohol to the same quantity
of acetic acid, and an equal volume of concentrated sulphuric
acid. Warm gently and notice the fruity smell of ethyl acetate.
Neutralise a few drops of acetic acid by adding excess of
ammonia and boiling until neutral. Let cool and add a drop
of ferric chloride. The red colour of ferric acetate is produced,
On boiling, basic ferric acetate is precipitated.
Heat a very small quantity of potassium acetate with an equal
bulk of arsenious oxide. The disagreeable and poisonous vapour
of cacodyl oxide is evolved.
4CH3.COOK + As203=As«>(CH3)40 + 2CO, -f 2K2CO3.
PREPARATION 10.
Acetyl Chloride, CH3.CO.C1.
Gerhardt, Ann. Chim. Phys., 1853, (3) 37, 285 ; Bechamp
Compt. rend.) 1855, 40, 944, and 1856, 42, 224.
50 grms. glacial acetic acid.
40     „    phosphorus trichloride.
Fit up the apparatus shown in Fig. 54. It consists of a distilling
flask (250 c.c.), which is attached to a condenser. A small
ACKTYL CHLORIDE

75

filter flask serves as receiver, the side tube being' attached
to a calcium chloride tube. The distilling vessel is provided
with a cork, through which a tap-funnel is inserted. The flask
is cooled in cold water in the \vater-bath (outlined in Fig". 54),
whilst the phosphorus trichloride is slowly run in from the tup-
funnel.* When the phosphorus chloride has been added, the
water in the water-bath is wanned to 40—50", until the evolu-
tion (if hydrochloric acid gas, which at first is very rapid, begins
to abate. The water-bath Is then heated to boiling until

•?s



Fie*. S4.

nothing  further distils.     The distillate is  no.v  redistilled as
before,  but   with  a  thermometer, and   the distillate collected

at the boiling point  of acefyl   chloride  (53    50).      Yield  45

grams,

Colourless liquid with a pungent smell ; it fumes
in contact with moist air ; b. p. 55 '» SP- g*°- 1*103 at 20'.
AVvjv//Wi.v, i. Add a few drops of aeetyl chloride to about
$ c.c. of water in a test-tube. The acetyl chloride sinks to the
bottom of the test tul H% but on shaking rapidly dissolves, and
hrat is evolved. The acetyl chloride is converted into acetic acid
and hydrochloric acid.
C'H:,.CCK:i f IUO    rH:i.CO,on f HCL
2. To about i c,c, of ethyl alcohol in a test-tube, add i c.c.
of acetyl chloride drop by drop, cooling under the tap. Then
76                PRACTICAL ORGANIC  CHEMISTRY

add about I c.c. of a solution of common salt. Ethyl acetate,
recognised by its fragrant smell, separates out on the surface of
the liquid.

CH3.COC1 + C2H5OH = CH3.CO.OC2H5 -f HCL

3. Add two drops of acetyl chloride to a drop of aniline. A
vigorous action occurs, and a solid separates. This is acetanilide,
and may be obtained in larger crystals by dissolving in boiling
water and cooling slowly.

CH3.COC1 + C6H5NH2 - C6H6NH.CO.CH3 + HCL
See Appendix\ p. 241.

PREPARATION n.
Acetic Anhydride (Diacetyl Oxide), cHg'cO/0'
.,•    Gerhardt, Ann. Chim. Phys., 1853, (3) 37, 311.
55 grms. sodium acetate (fused).
40    „     acetyl chloride.
A retort (250 c.c.) is attached to a short condenser and
receiver, which is furnished, as in the previous preparation, with
a calcium chloride tube. The tubulus of the retort is closed by
a cork, through which a tap-funnel is fixed. The fused sodium
acetate is prepared by fusing crystallised sodium acetate,
(CH3.COONa + 3H20). The sodium acetate (100 grams) is
,,                placed in a shallow tin and heated over a Bnnsen burner.
|                   It first melts in the water of crystallisation, after which it
• *                becomes solid, and finally melts again as the temperature rises.
When completely melted it is allowed to cool, powdered, and
introduced into the retort. The acetyl chloride is gradually
added through the tap-funnel, the retort being cooled in water.*
When the acetyl chloride has been added, the contents of the
,-                  retort are well stirred by means of a thick glass rocl pushed
through the tubulus. The retort is now closed by an ordinary
cork or stopper, and heated over a small flame, which should
be moved about to prevent the retort cracking. When nothing
ArKTAMIDK

77

further distils, the retort is allowed to cool somewhat, and the
distillate poured bark and redistilled. Kinally it is distilled
from a distilling flask with a thermometer, and collected at
i 30 i.jo . Yield ,|t> grains.

aUl'OCl -h t:n,,eO.ONa   - (CH3.CO)20 4- Nad

/V*yV;Y/>,v Colourless liquid with an irritating1 smell ; h, p.
i.»tf ; ^p- Kr- i'°K M 1 5 ''•

A'rWi //V*//,v Repeat the three experiments described undei
aei'tyl rhloride. The result is the same in each case ; but as
flic* acetic anhydride reacts less readily than aeelyl chloride, the
mixture requires to be wanned.

i.     !l*/() { u-°   2CiL,.(.:oon.

( > -i' ^a I !,-,( * ! I    ( : 1 13.C( ).OCuI I6 + C H,5.CO() I L
-<•) f QI IftNIL- (:aH6NH.CO.CIIn + CH,,

"

In Keatl'jon 2, combination is not <"omplete, even on boiling,
•tnd a little dilute caustic soda must be added to decompose the
unchanged acetic anhydride. In Reaction 3, the product remains
liquid until water is added, when it becomes solid, and on
heatinj.; dissolves, Sec* Afifrndiv^ p. 24,*.

1'KKi'ARA'nON    12.
Acetamide, (:Ils.(X).NII,,
IIt»fni:mn, AVr., 1882, 15, <;8i.
iix> jjrms. ammonium acetate.
Acc'tainide may b<« obtained by simply distilling solid
ammonium acetate from a distilling tlask provided with u thermo-
meter, nsinj* fur a condenser a straight, wide tube. (See Fig. 55.)
A considerable quantity of ammonia, water, and acetic acid
PRACTICAL ORGANIC CHEMISTRY

distils, and when the temperature passes 180° the distillate sol-
idifies, and consists mainly of acetamide'. The yield is, however,
small. A better result is obtained by first heating the ammonium

FIG. 55.

i

acetate in sealed tubes. The ammonium acetate, if not procur-
able, may be prepared by adding to 70 grins, glacial acetic acid,
warmed in a basin on the water-bath, about 80 grins, powdered
ammonium carbonate until the acid is neutralised, which is re-
cognised by diluting a sample with a little water, and testing
with litmus.

Heating under Pressure.—Two tubes are made from the
usual thick-walled tubing by sealing one end (see p. 24). These
are gently warmed, and the melted acetate poured in until they
are about half full. They are then sealed in the manner described
on p. 24. The tubes are then placed in a tube furnace (p. 23)
and gradually heated to 200°, at which temperature they are
maintained for 5—6 hours. Without removing the tubes from the
furnace they are allowed to cool, and the capillary end opened by
holding a Bunsen burner to the tip until fused, when the pressure
within perforates the glass. If a deep file scratch is then made
about an inch below the sealed end and the end of a red-hot glass
rod held against the scratch, a deep crack is produced and the end
easily removed. After heating, the tubes contain a clear,, oily-
looking liquid, which consists of an aqueous solution of acetamide,
together with some unchanged acetate. The contents are poured
into a distilling flask and distilled with a straight tube as
condenser, and the portion boiling above 180° collected in a

I
1
ACETONITRILE                                 79

small beaker. This distillate, on standing, almost completely
solidifies to a colourless crystalline mass. It is freed from
mother-liquor by spreading on a porous plate, and purified by a
second distillation. The acetamide has then a nearly constant
boiling-point. Yield, about 40 grams.
CH3.CO.ONH4 = CH3.CONH2 + H2O.
Properties.—Colourless, rhombohedral crystals, having a
peculiar smell of mice. This is due to impurity, which may be
removed by recrystallising from benzene ; m.p. 82°; b.p. 222° ;
easily soluble in water and alcohol.
Reaction,—l. Boil a small quantity of acetamide with caustic
soda solution. Ammonia is evolved, and sodium acetate is found                  |
in solution, CH3.CONH2 + NaOH = CH3.CO.ONa + NH3.
See Appendix) p. 243.
PREPARATION 13.
Acetonitrile (Methyl cyanide), CH3.CN.
Dumas, Malaguti and Leblanc, Annalen, 1848, 64, 332.
10 grms. acetamide
15     „     phosphorus pentoxide.
The phosphorus pentoxide is introduced into a small dis-
tilling flask (200 c.c.) attached to a short condenser. As the
pentoxide absorbs moisture rapidly and becomes sticky, it is
convenient to push the neck of the distilling flask through a
cork which fits the phosphorus pentoxide bottle, and then to
shake in the oxide until the required weight is obtained. The
powdered acetamide is immediately introduced and shaken up,
and the mixture distilled over a small flame, which is constantly
moved about. Add to the distillate about half its volume
of water, and then solid potassium carbonate, until no more
dissolves. The upper layer of liquid, which consists of methyl
cyanide, is separated and distilled over a little fresh phosphorus
pentoxide with thermometer. Yield, about 5 grams.
CH3.CO.NH2 - H2O = CH3CN.
Properties.—Colourless liquid with peculiar smell; b. p. 82°.
Reaction.—Boil a few grams of the acetonitrile with three
So                PRACTICAL ORGANIC CHEMISTRY

times its weight of a mixture of 2 vols. water and 3'vols. con-
centrated sulphuric acid for an hour with a long upright tube
or air-condenser. Distil a few c.c. of liquid, and test the distillate
for acetic acid, 2GH;,CN + H2S04 + 4H,O = 2CH:,COOH +
(NH4)2S04. See Appendix, p. 244-
PREPARATION 14.
Methylamine Hydrochloride, CH;>.NH:,.HC1.
Wurtz, Comptrend., 1848, 28, 223 ; Hofmann, 5fr., 1882, H,
2725, and JBer., 1883,15, 4°7 and 762.
20 grms. acetamide
54    „     (18 c.c.) bromine
56    „     caustic potash.
The dry acetamide and bromine are mixed in a flask (£ litre),
and whilst the mixture is cooled in water, a 10 per cent,
solution of caustic potash (about 20 grams KOH) is added,
until the dark brown liquid changes to a deep yellow colour.
The solution, which now contains potassium bromide and
acetmonobromamide, is slowly added from a tap-funnel in-
serted, together with a thermometer, into the neck of a distilling
flask (i litre). The flask contains a concentrated solution of
caustic potash (56 grams in 100 c.c. of water), heated to 60—70°.
Heat is evolved, and care must be taken that the rise of tem-
perature does not greatly exceed the above limits. The reaction
goes on quietly, and the yellow solution is gradually decolourised.
The mixture is then digested for a short time at the above
temperature until the yellow colour completely disappears. A
few bits of broken pot are now introduced into the flask, which
is closed with an ordinary cork, and the liquid distilled over
wire-gauze. The vapours of. methylamine and ammonia, which
are cooled, are passed by means of a bent adapter, attached to
I fl         * «                   the end of the condenser, into dilute hydrochloric acid contained
in the receiver. Care must be taken that the adapter does not
dip too far into the acid, or liquid may }>e sucked back into the
condenser and distilling flask. When the distillate is no longer
alkaline, and consequently all the methylamine has been driven
over, the hydrochloric acid solution is evaporated to dryness on
I
I
the water bath, and the colourless crystalline residue extracted
repeatedly with .small quantities of absolute alcohol, which
dissolves out the meihylaniinc sail from the ammonium chloride.
I'Yom the hot alcoholic solution foliated crystals separate out
on cooliin*.

.rONH, I- I Jr., -H KOII

* H.tiiiiilr.

<'H:,,<'ONinir !•• KOI I

rn:5,X;t";C)  !

(TLj.CONHBr 4- KBr + IU)

Ao'tiitouiiluunuuimir.

t'H:,.N:CX> H- KBr + H«O

. Large deliquescent tablets, which melt at 227",
and sublime, above that temperature, with slight decomposition.
The base is liberated on warming with caustic soda, as an in-
llammable j.;as with strong ammoniacal smell. See Appendix,
p. 245.
1'R FJU RATION   15.
Ethyl Acetate  (Acetic Ether), CH3.CO.OCaHfl.
Si herle, (.Vtt'w/ftt/ /i\v.sv/)',v, 1782, p. 307 ; Frankland, Duppa,
/'////. 7/vw.v., 1865, 156, 37 ; l*iibst, Hull. Soc. t'//////., 1880, 33,
•;t).
50 c,c, cone, sulphuric acid.
50 c.c. absolute alcohol.1
Mixture of equal volumes of glacial acetic: acid (icx^c.c.)
and absolute alcohol (K.X.J <:.c.).
A distilling flask (A litre) is attached to a condenser and
receiver, The She.!; in provided with a cork, through which a
separating funnel is inserted. The mixture' of 50 c.c. of con-
centrated sulphuric and and 5° (>'('- <*f absolute alcohol is
poured into the flank, which is then heated in a bath of paraffin
wax or fusible metal"* to 140, and kept at this temperature.
The mixture of equal volumes of acetic acid and alcohol is
J ,-1/fMv/ »*• fittis w,«v '»'' n».«l«*»n IINM inc'ly thr f,Mw way, untnp, methyl ukohol.
Tll«t |*I'««iu« I i-. ihrsi f>,ii'!i>*n.t(Mi ;ilid (itllt'rtni at  ',7     tt\".
a A lu-al»I»' «»«-t;tl (Milt li.v. ili«' ;ulviUii;ttt<' uv«''' "»» "il'l««h of ttrtttirr ^nirlting uor
l»*iiit: li.iMr tiM'iitih fi»«% h i% ittailr by nulling »n a smalt ntokiiiK i»an one' part
ttl Irtui uutl IWL» |»,ul-» til hKumtii. Thi-i alloy is llttkl abovt? iat>".
82                PRACTICAL  ORGANIC CHEMISTRY
"now added, drop by drop, from the tap-funnel at the speed at
which the liquid distils, as in the preparation of ether (p. 59)
When all the mixture has been added, the distillate, which con-
tains the ester, and also acetic acid, alcohol, ether, and
sulphurous acid, is shaken in a separating funnel with a strong
solution of sodium carbonate (50 c.c.) until the upper layer of
ethyl acetate ceases to redden blue litmus. The lower layer is
removed as completely as possible, and a strong solution of
calcium chloride (50 grams in 50 c.c. of water) added, and the
shaking repeated. The lower layer of calcium chloride is run
off, and the ethyl acetate carefully decanted from the mouth of
the funnel into a dry distilling flask. A few pieces of solid
calcium chloride are added, and, after standing over night, the
ethyl acetate is distilled from the water-bath with a thermo-
meter in the neck of the flask. The portion distilling below
74° contains ether, that boiling at 74—79° is mainly ethyl
acetate, and is separately collected. Yield, 80 per cent, of
the theory.
C2H5(OH) + H2S04 = C2H5.H.S04 + H,O.
C2H5HSO4 + CH3:CO.OH = CH3.COOC2H6 +"H2SO4.
Properties.—Colourless liquid, with an agreeable fruity smell;
b. p. 77°; sp. gr. 0-9068 at 15°; soluble in about u parts of
water ; miscible in all proportions with alcohol, ether, and acetic
acid,
Reaction.—Weigh out 20 grams of ethyl acetate, and heat in a
round flask with three times its volume of aqueous potash
(iKOH : 3H2O) with upright condenser over wire-gauze*. Add
a small piece of porous pot to prevent bumping. After an hour
or so the upper layer of ethyl acetate will have disappeared. Distil
the product with a thermometer.until the temperature reaches
100°. Add solid potassium carbonate to Aie distillate until no
more dissolves. Separate the top layer of alcohol and dehydrate "
over fresh potassium carbonate or quicklime. Distil with a
thermometer and weigh the distillate. Neutralise the alkaline
liquid, from which the alcohol was fust distilled, with dilute sul-
phuric acid, and evaporate to dryness on the water-bath. Break
up the solid resjdue, and distil with concentrated sulphuric acid
(20 c.c.) until the thermometer marks 130°. Redistil and collect
ETIIVL ACF.TOACICTATE

between 115° and 120°.    Weigh  the  distillate.    This process
furnishes an example of fiytfwlysis or saponijication,
CH;t.COOCaHr, + H,O - CH.,.COOH + C2HfiOH.
See Appendix, p. 247.
PREPARATION 16.
Ethyl Acetoacetate (Acetoacetic Ester),
c: H 3. c: o. c H B. c o. o c, 11 f).
Geuther, JaJtrcsb., 1863, p. 323; Frankland, Duppa, . Phil
Tram., 1865, 156, 37 ; Wislicenus, Annalen, 1877, 186, 161.
200 grms. ethyl acetate.
20     „     sodium.
The ethyl acetate, carefully dehydrated as described in the
previous preparation, is introduced into a round flask (4 litre)
connected with a long upright condenser. 20 grams well pressed
sodium, cut into thin slices, are quickly added, and the flask
cooled in water. After a short time a brisk reaction sets in, and
ultimately the liquid boils. When the first action is over, and
no further evolution of heat occurs, the mixture is heated on the
watcr-b.'ith, without detaching the condenser, until the sodium is
completely dissolved. A 50 per cent, acetic acid solution is at
once added and well shaken, until the liquid is acid, (about
TOO c.c), and then an equal volume of concentrated brine. The
liquid divides into two layers ; the upper one, consisting of
acetoacetic ester and unchanged ethyl acetate, is carefully
separated. Jt is distilled over wire-gauxe until the thermometer
marks 100°, and all the ethyl acetate has been removed. The
distillate is now collected in five fractions (roo 130'', 130—135°?
165—175°, 175-185°, 185—200"). The fraction distilling at
* 175—185° is nearly pure acetoacetic ester. Yield 30—40 grams.
A further quantity may be obtained by redistilling the other
fractions ; but it is undesirable to repeat the process frequently,,
as acetoacetic ester gradually decomposes at the boiling point.
It is for this reason that Gattennann recommends the fractional
distillation to be carried out in vttcito.
The brown residue remaining in the distilling flask solidifies,
on cooling, to a crystalline mass consisting chiefly of dehy-
G   2
g4               PRACTICAL ORGANIC  CHEMISTRY

dracetic acid CSH8O4. . It is converted into the sodium salt t>y
boiling with soda solution with the addition of animal ch&r-
coal. & The sodium salt crystallises from the nitrate. O&
adding dilute sulphuric acid, the free acid is obtained as colour-
less needles ; m. p. 109°.

i. 2C,H5OH + Na2 = 2NaOC2H5 + H2

/ONa
2   CILCO.OC.,H5 + NaOC«HB= CII3

.                     "

/ONa

+ 2C2HSOH.

CO.OCoHfl + C

+ CH,:CO.ONa

The formation of ethyl acetoacetate occurs, according- to
Claisen, in four steps. The presence of a small quantity of
alcohol gives rise to sodium ethylate, which forms an additive
compound with ethyl acetate. The latter unites with a second
molecule of ethyl acetate yielding the sodium salt of ethyl aceto-
acetate, and splitting off alcohol, which reacts with fresh metallic
sodium. The sodium salt on acidifying passes into the tauto-
meric (ketonic) form of acetoacetic ester.
Properties.—Colourless liquid possessing a fruity smell ; b. p.
181°; sp. gr. 1*03 at 15°. Boiled with dilute caustic potasli,
the ester decomposes into alcohol, carbon dioxide, and acetone
(ketonic decomposition), with strong or alcoholic caustic potasli,
sodium acetate and alcohol are formed (acid decomposition).
Reactions.—i. Add a drop of ferric chloride dissolved in alcohol
to a few drops of the ester ; a deep violet coloration is produced.,
2. Add i c.c. of a saturated alcoholic solution of cupric acetate
to a few drops of the ester, a bluish-green crystalline precipitate
of copper acetoacetic ester, (CcH9O3)2Cuj is formed See
Appendix, p. 248.                             "                                jv";
Distillation in vacuo.—The apparatus is shown infcig-. 56.
The distilling flask is provided with a thermometer and attach eel
to a short condenser and receiver. The receiver consists of a.
DISTILLATION   IN   YACl'O                        <S5

second distilling flask, which is tightly attached to the end of
the narrow condenser tube, figured at ti and connected by the
side limb by means of pump-tubing to a water-jet aspirator and

mercury-gauge. Some small bits of porous pot are placed in
the flask, which is heated in a paraffin bath, and the apparatus
exhausted to about 35 — 40 mm. pressure. At this pressure ethyl
acetoacetate boils at about 90". The following table gives the
temperatures corresponding' to different pressures :-•••

74-i '
88'

14,

94
97 '

ICK)

- 45
80

The chief inconvenience which attends distillation iwntcito is
the bumping of the liquid in the, distilling ilask. This may be
moderated or removed by various devices, such as the introduc-
tion of porous pot, capillary glass tubes, &c., or by driving a
rapid stream of fine air-bubbles through the liquid. For this
purpose a Claisen flask (Fig'. $7), may be used with advantage.
A tube is drawn out into a fine capillary and is open at both
ends, the wide end being attached to a. short piece of rubber
tubing and screw-clip. This tube is inserted through a cork in
86

PRACTICAL ORGANIC CHEMISTRY

the straight neck of the flask, whilst the thermometer is fixed
in the second neck, which is attached to the condenser Trie
stream of air-bubbles is regulated by the clip. Instead of trie

FIG.

long manometer shown in Fig. 56, a more compact, and, for
low pressures, a more convenient form is shown in Fig". 5^-
If the distillate has to be separated into fractions, it is unde-
sirable to interrupt the boiling. Various forms of apparatus
for effecting this object are shown in Figs. 59—61. Tfre
apparatus (Fig. 59) consists of a double receiver a and b ; c and
e are ordinary two-way taps, whilst d is a three-way tap pierced
lengthwise and crosswise as shown in section at f. Trie

FIG. do.

FIG. 61.

aspirator is attached to the limb marked with the arrow. During"
the distillation the taps c and d connect the apparatus with, trie
aspirator whilst e is closed. The distillate collects in a. Wrien
this fraction is to be removed, c is closed and e is opened. Tlie
r,OK.\CKTIC ACID

liquid is thereby transferred to the second receiver b; c is now
closed, c is opened and tf turned so as to let: air into b ; b may
now be removed and replaced by a similar vessel and the pro-
cess repealed. Fig. 60 needs little explanation. There are two
or more receivers on one stem. P>y rotating the stem the dis-
tillate falls into one or other receiver. Fig. 61 consists of a
vacuum vessel containing a series of test-tubes which can be
moved in turn, under the end of the condenser, by means of a
vertical axis. It is often preferable to beat the distilling" flask
in an oil or metal bath instead of using wire-gauze. Distilling
flasks above 250 c.c. capacity should not be used for low pres-
sures, as they may collapse. For high boiling liquids, or for
substances which may solidify in the condenser, a condenser
tube without water-jacket is used. A convenient form of con-
denser tube is shown at <i, Fig. 56. It consists of straight tube
fused on to a short narrower tail-piece. In certain cases it is
found convenient to insert the side-tube of the distilling flask
directly into the neck of the. receiver (see p. 94).
PRKPARATION 17.
Monochloracetic Acid, CH.jCI.CO.OH.
•    R. Hofmann, Anna/en, 1857,102, i ; Auger, Behal, Bull. Soc.
Chim,, 1889, (3)2, 145-
roo c.c. glacial acetic acid.
10 grins, sulphur (flowers).
Fit up the apparatus shown in Fig. 62.* It consists of a stone-
ware jar one-third full of pyrolusitc in lumps, and fitted with exit
tube and tap-funnel. It is heated on a sand-bath over a small
flame, whilst concentrated hydrochloric acid is allowed to drop
in from the tap-funnel. A rapid current of chlorine is thus
evolved, which is dried by passing through concentrated sul-
phuric acid in the Woulff bottle. The Woulff bottle has a safety
and exit tube, the latter being connected with a straight tube
passing to the bottom of the retort. The retort is tilted upwards
and connected with an upright: condenser, which is furnished
with an open calcium chloride tube. The. acetic acid and sul-
phur are placed in the retort, and heated on the water-bath.
The retort and contents are weighed at the commencement of
the operation on a rough balance. A, rapid current of chlorine
PRACTICAL  ORGANIC  CHEMISTRY

is then passed through for six to twelve hours, .and the retort
occasionally weighed, until the increase in weight (50 grains)
roughly corresponds to the formation of monochloracetic acicl.
The operation is then stopped. The action of the chlorine is
greatly facilitated by sunlight. The yellow liquid in the retort
is decanted from the sulphur into a distilling flask, and distilled
over wire-gauze. Some acetyl chloride, sulphur chloride, and
unchanged acetic acid first distil, after which the temperature

FIG. 62.
rises and the fraction boiling at 150°—190° is collected separately.
It is advisable to run the water out of the condenser when the
temperature approaches 170°, as the acid may solidify and bloclc
the condenser-tube. The distillate solidifies on cooling-. Any
liquid is drained off at once, and the solid is redistilled and col-
lected at i So0—190°. It is nearly pure chloracetic acid, Yield
80—100 grams.
CH3.CO.OH + CIa = CH2C1.CO.OH + HC1.
The sulphur acts as a "chlorine carrier" by forming sulphur
chloride.
Properties.—Colourless crystals ; m. p. 63°; b. p. 185°—187° ;
readily soluble  in  water,-and  deliquescent  in  moist  air.    It
causes blisters on the skin.    See Appendix, p. 252.
MONOBROMACETIC ACID

PREPARATION 18.
Monobromacetic Acid, CH2Br.COOH.

Hell,  Bcr.)   1881,   14,   891 ;   Volhard,   Annalen,  1887,  242,
141 ; Zelinsky, Ber., 1887, 20, 2026.

30 grms. (30 c.c.) glacial acetic acid.
I05     3)      (35 c.c.) bromine.
5     „       red phosphorus.

All the above substances must be dry. The acetic acid is frozen in
ice, and any liquid drained off, and the red phosphorus is washed
with water to free it from phosphoric acid, dried in the steam oven,
and kept over sulphuric acid in a desiccator until required. The
bromine is placed in a separating funnel with half its volume of
concentrated sulphuric acid overnight, and
then separated. The apparatus is shown in
Fig- 63 . It consists of a round flask (250 c.c.)
attached to an upright condenser, which is
provided with a cork. A tap-funnel con-
taining the bromine passes through one
hole, and a wide bent tube, attached at its
lower end to a funnel, passes through the other.

As a large quantity of hydrobromic acid is

evolved in the reaction, the funnel is made to

touch   the  surface  of water  contained  in a

beaker,   whereby  it  is completely  absorbed.

The phosphorus and acetic acid are placed

in the flask, and bromine dropped in from the

tap-funnel.*    A vigorous reaction occurs, and

the  liquid becomes  very  warm.    After half

the   bromine    has   been   added   the   action

moderates, and the remainder may be run in

more  quickly.    When  the  whole   has  been

added,   the   liquid  is  boiled   gently until  the  colour  of the

bromine   disappears.     It   is  now   allowed   to  cool,   and the

liquid decanted into a distilling flask for distillation in vacua.

Care must be taken not to touch the substance with the hands,

as even a small quantity produces very unpleasant sores.    The

apparatus for distilling in vacua is shown in Fig. 56 (p. 85).

FIG. 63.
go                PRACTICAL  ORGANIC  CHEMISTRY

The distilling flask is provided with a thermometer, ancl attached
to a short condenser and receiver. The receiver consists of a,
second distilling flask, which is tightly attached to the end of the
condenser and connected by the side limb with pump-tubing to
a water-jet aspirator and mercury manometer. Some small
bits of of porous pot are placed in the flask, and the apparatus
exhausted to about 50 — 60 mm. pressure. The liquid distils at
a nearly constant temperature (about 50° — 53°), and consists of
nearly pure bromacetylbromide. The calculated quantity of
water is added to convert it into bromacetic acid, when the liquid.
forms a solid crystalline mass.*1 It may be purified by distilla-
tion at atmospheric pressure with condenser-tube only, the
portion boiling above 165° being collected separately.

3-CH3.COOH + P + nBr = sCH2Br.COBr + HPO;} + sHBr.

Bromacetyl bromide.

CH2Br.COBr. + H2O = CH2Br.CO.OH + HBr.

Bromacetic acid.

Properties. — Colourless crystals; m. p. 50° — 51°; b. p. 208°.
See Appendix, p. 252.

PREPARATION 19.
Grlycocoll (Glycine, Aminoacetic Acid).    CH2

Braconnot, Ann. Chim. Phys., 1820, (2) 13, 114; Perkin,
Duppa, Trans. Chem. Soc., 1859, 11, 22 ; Kraut, Annalen^ 1891,
266, 292.
50 grms. chloracetic acid.
50 c.c. water.
600 c.c. ammonia, 26*5 per cent. (sp. gr. 0*907 at 14°).
Fit up the apparatus shown in Fig. 64. It consists of a large
wide-necked bottle, in which the ammonia solution is placed.
The solution is stirred by a mechanical stirrer, rotated by means
of a water-turbine. The solution of the chloracetic acid in 50
c.c. water, is dropped in from a tap-funnel After standing
24 hours the liquid is poured into a flask, ancl the excess of
ammonia is removed by passing in a current of steam, ancl
evaporating at the same time on the water-bath until the last
traces of ammonia disappear. The solution now contains gly-
cocoll and ammonium chloride. Precipitated carbonate of copper
is added to the hot liquid until no further effervescence occurs,
and some carbonate remains undissolved. It is filtered and
evaporated down on the \vater-bath until crystallisation sets in.
This is determined by removing and cooling a small portion in
a test-tube or watch-glass. The blue needles of copper glycocoll,
(CoH.jNO^Cu.H.jO, are tillered and washed, first with dilute and
then with stronger spirit. The mother liquor may be further eva-
porated, and. a. fresh quantity of crystals obtained. The copper
salt is dissolved in water and precipitated hot with hydrogen
sulphide, the free glycocoll passing- into solution. The pre-
cipitate is filtered and well washed, and the filtrate evaporated

to a small bulk on the water-hath. Crystals of glycocoll
separate out. Yield 15-20 grams. The loss is due to the
formation of di- and triglycolaminic acid, NH(CIL.COOH),,
andN(Cn,C()()H),.

CILCI.COOIJ

+ NH4CI.

Fro forties. Large monoclinic crystals ; discoloured at 228° ;
m.p. 232-236° ; scarcely soluble in alcohol and ether, readily
soluble in water (r part glycocoll in 4 parts water).
Rcuction.— \. Add a drop of copper sulphate to a solution of
g'lycocoll, and notice* the blue colour of the copper salt.
2. Add a drop of ferric chloride to the solution. It gives a
deep red colour. See Appendix^ p. 254.
PRACTICAL ORGANIC CHEMISTRY

PREPARATION 20.

CHg.NHa.HCl
Q-lycocoll Ester Hydro chloride,   \

CO.OC2H-

Klages, Ber., 1903, 36, 1506, Hantzsch and Silberrad,
1900, 33, 70.

250 c.c, formaldehyde solution (40 per cent.).
90 grams ammonium chloride (powdered).
1 10     „     potassium cyanide (in 200 c.c. water).
63 c.c. glacial acetic acid.    "

The first part of the process consists in the preparation of
methyleneamino-acetonitrile.

The formaldehyde and ammonium chloride are mixed in a
wide-necked glass jar cooled in a freezing mixture and
stirred by means of a stirrer as shown in Fig. 64. When the
temperature falls to 5° the potassium cyanide solution is slowly
run in from a tap-funnel during three hours, the temperature
being maintained below 10°. When half the cyanide solution
has been added the ammonium chloride will have com-
pletely dissolved. Whilst the second half of the solution is
being added, 63 c.c. of glacial acetic acid are dropped in from
another tap-funnel at about the same rate, whilst the tempera-
ture is kept below 15°. As soon as the acetic acid is
added a white 'crystalline substance begins to separate and
gradually fills the liquid. The stirring is continued for another
hour after the solutioris have been added. The crystalline mass is
filtered, washed with water and dried. The yield is 60 — 70 grams.
Methyleneamino-acetonitrile melts at 1 29°. 1 1 m ay be recrystallised
from alcohol, but is usually pure enough for further treatment.
On hydrolysis in presence of alcohol it breaks up into glycocoll
ester hydrochloride, ammonium chloride and formaldehyde.
CH2:N. CH2CN + 2H2O + C2H5OH -I- HC1 = (HCl)NHa, CH0. COOC,HB
+ NH4C1 + CH20.
Twenty-five grams methyleneamino-acetonitrile are added to
170 c.c. of absolute alcohol previously saturated in the cold
with hydrogen chloride.
GLVCOCOLL KSTER HYDROCIILORIDE

93

PIG. 65.

Preparation of Hydrogen Chloride.—A filter flask
(J, litre) is fitted with a rubber cork, through which a tap-
funnel is inserted. The flask is filled one-third full of con-
centrated hydrochloric acid and is attached to a wash-bottle
containing' a little concentrated sulphuric acid. A delivery
tube is attached to the wash-bottle. The hydrogen chloride is
generated by dropping concentrated sul-
phuric acid from the tap-funnel into the
flask containing the hydrochloric acid.
As the gas is rapidly absorbed by the
alcohol and may in consequence run
back into the wash-bottle, it is advis-
able to run in the acid rather more
quickly at the beginning than is neces-
sary later on and to generate the gas
for a short time before passing it into
the alcohol. The apparatus is shown
in Fig. 65.
When saturated, the mixture is boiled
for an hour with reflux condenser on
the water-bath and filtered hot from the ammonium chloride
which remains undissolved. On cooling, the greater portion of
the ester hydrochloridc crystallises. A further quantity may be
obtained by concentrating the mother liquors. Yield 30—35
grams.
J*r<>/>tT//cs.~ Colourless needles ; m. p. 144°, soluble in hot
alcohol, very soluble in water.
G-lycocoll Ester Hydrochloride from Gelatine.
Mix 100 grams commercial gelatine or size with 300 c.c. con-
centrated hydrochloric acid and shake until the gelatine is nearly
dissolved ; then add a few fragments of porous pot and boil
over wire gau/e with reflux condenser for four hours. The
dark coloured product is now evaporated on •< the water-bath
under diminished pressure in the apparatus shown in Fig. 66.
It consists of two distilling flasks (i litre) fitted together by
rubber corks, the one acting as distilling flask and the other as
receiver. The receiver which is cooled by a stream of water
is attached to a water-jet aspirator. A long capillary, which
nearly touches the bottom of the flask, is inserted through the
94

PRACTICAL ORGANIC CHEMISTRY

cork of the distilling vessel. It serves to agitate the liquid
by introducing a stream of fine air-bubbles which keep it
in constant motion. When the water is removed as far
as possible, the residue, which forms, on cooling, a thick
viscid mass, is mixed with 500 c.c. absolute alcohol. It is
heated on the water-bath with reflux condenser for a short time
with the addition of a little animal charcoal and filtered. The
alcoholic solution is cooled in ice and saturated with dry
hydrogen chloride (see p. 93). The liquid is then boiled for

FIG. 66.
half an hour on the water bath, cooled, and, after dropping in a
crystal of the substance, left overnight. Glycocoll ester hydro-
chloride crystallises in colourless needles (m. p. 144°) and is
filtered and washed with a little alcohol. Yield 10—15 grams.
PREPARATION 21.
CH<J|
Diazoacetic Ester,    |    \N
COOC2H6
Curtius, /. prakt. Chem.,  1888, 38, 401 ; Siiberrad,  Trans.
Chem. Sac., 1902, 81, 600.
25 grams glycocoll ester hydrochrloride (in 50 c.c. of water).
18      ,,      sodium nitrite in fine powder.
DT A/0ACETIC ESTER                           95

The glycocoll ester and sodium nitrite are shaken together in
a separating funnel (250 c.c.) until the nitrite is dissolved, a
little water being added if necessary. Fifteen c.c. of ether are
poured into the funnel, and when the temperature has sunk to
about 5' , two or three drops of a ten per cent, sulphuric acid
solution are added. The mixture is now well shaken for a
minute and the aqueous layer drawn oft" into a flask standing in
ice whilst the yellow ethereal solution, separated as completely
as possible from water, is poured from the neck of the funnel
into a dry flask. The aqueous portion cooled to 5° is returned
to the funnel and the process is repeated five or six times with
fresh quantities of ether, a few drops of sulphuric acid being-
added each time before shaking, and the yellow ethereal layer
separated, until the ether is only slightly coloured.

The united ethereal extracts are shaken with very small
quantities of sodium carbonate solution until no more carbon
dioxide is evolved and the solution remains alkaline. The
ether solution is then thoroughly dehydrated over calcium
chloride over-night and the ether carefully i*emoved on the
water-bath, which should not be heated to boiling. When most
of the ether has been distilled off, the flask is taken from the
water-bath and the remainder of the ether removed by blowing
air over the surface of the liquid. Yield about 15 grams.

Properties. — Deep yellow liquid which explodes on boiling ;
but distils undecomposcd under diminished pressure.

Reactions.— Add a drop of the diazoacetic ester to con-
centrated sulphuric acid. It decomposes explosively. Heat a
few c.c. of the ester in turn with water and alcohol. Nitrogen
is evolved with the formation of glycollic ester in the first case
and ethyl glycollic ester in the second.

Add an ethereal solution of iodine. Nitrogen is evolved and
iodacetic ester is formed. TIeat a little of the ester with
concentrated hydrochloric acid. Nitrogen is evolved and
chloracctic ester is formed. Gradually add five grams of the
diazoacctic ester to a solution of 8 grams of caustic soda
96                 PRACTICAL ORGANIC CHEMISTRY

dissolved in 12 c.c. of water heated on the water-bath. A
vigorous reaction occurs and yellow crystals of sodium bis-
diazoacetate are deposited. Cool, add 10 c.c. of spirit, and
filter and wash with spirit.

N = N\

>CH COONa

See Appendix ; p. 255.

PREPARATION 22.

Diethyl Malonate.

Conrad, Annalen, 1880, 204, 126; W. A. Noyes, Amer.
Chem.J.) 1896, 18, 1105.
50 grms. chloracetic acid (in 100 c.c. water)
40     „    potassium carbonate
40     35    potassium cyanide (in powder)
The solution of chloracetic acid is poured into a wide basin
(20 cm. diam.), and whilst the mixture is heated to 55 — 60°
potassium carbonate (40 grms.) is added until the evolution of
carbon dioxide ceases and the liquid is neutral. A solution of
potassium chloracetate is thus obtained. Potassium cyanide
(40 grms,) is now added and well stirred.* When the first
reaction is over, the contents of the basin are cautiously heated
on 'the sand-bath, whilst the mass is continuously stirred with a
thermometer until the temperature reaches 135°. The brown
semi-fluid mass is allowed to cool and stirred whilst solidifying,
and then quickly broken up into coarse powder and introduced
into a round flask (J litre). The potassium cyanacetate which has
been formed is now converted into the ester, and at the same
time hydrolysed by boiling with sulphuric acid. Absolute
alcohol (20 c.c.) is gradually added with shaking, and the flask
is then mounted on a water-bath and attached to a reflux con-
denser. A cold mixture of 80 c.c. absolute alcohol and So c.c.
concentrated sulphuric acid are added in the course of about ten
minutes, and the flask heated for one hour on the water-bath.
The mixture is cooled quickly, 100 c.c. of water added, and any
KTIIYL  MALUKU.: ACID                          07
insoluble matter filtered off. The (liter is washed several times
with small quantities of ether, and the filtrate .shaken up with the
ether and separated. The filtrate is shaken up repeatedly with
fresh ether until the ester is completely separated, and the united
ethereal extracts freed from acid by shaking with a strong solu-
tion of sodium carbonate until the latter remains alkaline. The
ether extract is then separated, dehydrated with calcium chloride,
and the ether removed on the water-bath. The residual ester is
distilled under reduced pressure. Yield 45 -50 grains.
CILCLCOOIC I- KCN -:CI I,CN.('( X )K + KCl
CIUJN.COOK-|-2C,1I0OIM 2lI,S()t.....(MI,(C()()(:.,IIr))., I KIISOi
I NII,,IiS<)t.
rropcrties. —Colourless liquid ; b. p. 195" \ sl}- g1"- roott at rS'*
See Appendix, p. 256.
PUMP A NATION 23.
Ethyl Malonic Acid, C,II;>.(;il( ^[|
Conrad, Anna!en, 1880, 204, 134.
16    gnus, ethyl malonate
25       „    (32 c.c.) absolute alcohol
2'3     „    sodium
20       „    ethyl iodide.
Sodium ethylate is first, prepared by dissolving 2*3 grams
sodium in 25 grains alcohol, and the reaction completed, if
necessary, on the water-bath as described on p. 83. Whilst
the product is still slightly warm, in grams nudonic ester aio
added from a tap-funnel. The liquid remains clear at first, but
before the ester has all been added a white crystalline body
(sodium ethyl malonate) separates out, and soon the whole
solidifies. To the solid mass 20 grams ethyl iodide are slowly
added. The mass softens and, after continued shaking, com-
pletely liquefies with evolution of heat. The product is now
heated on the water-bath, when it becomes turbid from the
separation of sodium iodide in the form of a fine powder. After
one and a half hours the liquid ceases to be alkaline and the
reaction is complete. The alcohol is distilled off from a brine-
bath (water saturated with common sa,lt) On the addition of
COHEN'S ADV. p. u. c.                                                n
98                PRACTICAL ORGANIC CHEMISTRY
water to the residue an almost colourless oil separates out. Xlie
oil is removed by extraction with ether, dehydrated over calcium
chloride and distilled. When the ether has been driven off,
almost the whole of the residue (ethyl diethyl malonate) passes
over at 206—208°. Yield about 15 grams.
CH2.(CO.OC2H8)2 + NaOCoH5 = CHNa(CO.OC2H5).2 + C
Sodium ethyl malonate.
CHNa(CO.OQ>H5)2 + C2H5I = CH(C9HB) (CO.OC2H5)2
Ethyl malonic ester.
Properties.—Colourless liquid with an agreeable fruity smell ;
b. p. 207°, sp. gr. rooS at 18°.
To obtain the free acid, the ester is hydrolysed \vitb
caustic potash. To 15 grams caustic potash in strong
aqueous solution, 10 grams of the ester are slowly added
from a tap-funnel. At first an emulsion forms, which soon
solidifies to a white mass. This is heated on the water-
bath with frequent shaking for about three-quarters of a.n
hour, until* it becomes completely liquid. The hydrolysis is
then complete. The product is diluted with a little water,
neutralised with concentrated hydrochloric acid, and. the free
acid precipitated with a strong solution of calcium chloride
as the calcium salt. This is separated from the solution "by
filtration and concentrated hydrochloric acid added to the
calcium salt. From the acid solution the free ethyl maloriit:
acid is extracted by shaking with ether. After evaporating*
off the ether, the acid remains behind as a syrup, wnicli
solidifies when cold. This is redissolved in water, boil eel
with a little animal charcoal to free it from any adhering
colouring matter, filtered, and evaporated to syrupy con-
sistency on the water-bath. The colourless acid crystallises
on cooling. Yield about 5 grams.
C2H5CH(CO.OC2H5)2 + 2KOH = CoH5CH(COJC)0 + 2C2H5OII
C2H5CH(Cb2K)2 + 2HCl = QH5CH(COSH)8-+ 2KC1.
Ethyl malonic acid.
Properties.—Rhombic prisms; m. p. 111*5°, easily soluble in
water, alcohol, and ether.
Reaction.—i. Heat a gram or two of the acid in a test-
tube over a small flame and have at hand a second test-tutee
one-third full of lime water. The acid decomposes at i<3o s
into butyric acid and carbon dioxi$£.   *|Vl\en the effervesce
begins to  slacken, decant  the  gas^mvn^
tube of lime-water, shake up  and noti^,tIife'Vi@^t)0 fTfe
acid which remains will have a strong smeTT"^^

C2H6CH(CO3H)2 = C3H7CO.OH + C02
See Appendix, p. 256.

Chloral Hydrate, CC13.C

Liebig, Annalen, 1832, 1, 189; Dumas, Aim. Chim. Phys.
1834, 56, 123.

Chloral hydrate is obtained by the action of chlorine upon
ethyl alcohol. The solid chloral alcoholate is formed,
CC13.CHOH.OC.2H5, which, when decomposed with sulphuric
acid, yields chloral, CC13.COH, a liquid which combines with
water to form the crystalline hy'drate.

Properties.—It crystallises in prisms, which dissolve easily in
water, alcohol, and liquid hydrocarbons. It has a peculiar
smell ; m. p. 57°; b. p. 97*5°. It volatilises on evaporating its
aqueous solution.

Reactions.—i. Add a few drops of a solution of chloral
hydrate to a little ammonio-silver nitrate solution and warm.
Metallic silver will be deposited.

2.  Add a little caustic soda to a solution of chloral and warm
gently.    The heat of the hand is sufficient for the purpose.    A
smell   of   chloroform   is  at   once   apparent,  CC13.CH(OH)2 +
NaOH==CHCl3 + HCO.ONa-hH.,O.    Sodium formate remains
in solution.

3.  Add a few drops of ammonium sulphide solution and warm
gently.    A brown colouration or precipitate is formed.

PREPARATION 24.
Trichloracetic Acid, CC13,CO.OH.

Dumas, Compt. rend., 1838, 8, 609 ; Clermont, Ann. ChiiiL
PAvs., 1871, (6), 6, 135-

25 grms. chloral hydrate

20     3,    fuming nitric acid ; sp. gr. 1 '5 (see p. id).

ioo              PRACTICAL ORGANIC CHEMISTRY
The chloral hydrate is melted in a distilling flask (250 c.c.) and
the fuming nitric acid added.* The mixture is heated carefully
over a small flame until the reaction sets in. After a few
minutes red fumes are evolved, consisting mainly of nitrogen
tetroxide. The reaction proceeds without the application of
heat, and is complete when, on warming the liquid, nitrous
fumes cease to come off. The product is now distilled ; below
123° excess of nitric acid distils ; between 123° and 194° n.
mixture of trichloracetic acid and a small quantity of nitric acicl
pass over, and at 194—196° nearly pure trichloracetic acicl
collects in the receiver and solidifies on cooling. It is advisable
to distil the last fraction with a condenser-tube only. The
fraction boiling at 123—190° is treated with a fresh quantity of
fuming nitric acid (10 c.c.), and the product- purified as before.
Yield, 10—15 grams.
CC13.CO.H + O = CC13.CO.OH.
Properties.— Colourless, rhombohedral crystals ;   m. p. 52° ;
b. p. 195°.    See Appendix, p. 257.
PREPARATION 25.
CO.OH
Oxalic Acid,     |             +2H0O
CO.OH
Scheele (1776), Naumann,   Moeser,   Lindenbaum, /.
Cham. 1907, 75, 146.
140 c.c. cone, nitric acicl.
20 grins, cane sugar.
o'l grm. vanadium pentoxide.
The nitric acid is warmed gently on the water-bath in a
flask(i litre) with the addition of the vanadium pentoxide. It Is
then placed in the fume cupboard and the cane sugar at onc<*
added. As soon as torrents of brown fumes begin to be evolved,
the flask is placed in cold water. After the reaction has ceasecl tli o
liquid is left for twenty-four hours when colourless crystals of
the acid separate. A further small quantity may be obtained
from the mother liquor on standing. The crystals are drained on
a small porcelain funnel without filter paper, and recrystallisecl
from a very small quantity of water. Yield, 15—20 grams.
MKTHYL OXALATK

Properties.— Colourless crystals, which, on heating to 100°,
lose their water of crystallisation, inch, arid then partly sublime
and partly decompose, giving off carbon dioxide and formic
acid. M. p. of the hydra.ted crystals ioi'5'J. Soluble in water
and in alcohol, very slightly soluble in ether.

Rcnctions.— i. Boil a little of the acid with ammonia solution
until neutral, and add calcium chloride solution. A white pre-                 • '!/

cipitate of the calcium salt is obtained, which is insoluble in                     $'

acetic acid.                                                                                                   ti i Jv

2. Add to   a  solution   of   the   acid  a  few  drops  of   dilute                    'i*

sulphuric acid, and warm gently.     On   adding  permanganate                   } »'

solution it is immediately decolourised, 5(.!.,!I„(.).1 + 2KMnOi+                  i   l\

^_3- Heat two or three grams of the crystals with about 5 c.c. con-                    t ^

centrated sulphuric acid.     Rapid effervescence occurs, and the                    *    (

gas maybe ignited at the mouth of the tube, C2H.>O.i —I.I.,O =                    ^ »

See Appendix^ p. 257.                                     "                         >y

PREPARATION 26
CO.OCU,
Methyl Oxalate, |
CO.ocil.,
Dumas, Peligot, yf;/;/. Chim. /Yw.T 1836,58,44; Krlenmeycr,
Rep. Phann. (2), 23, 432.              '         '                                                       'M
70 grins, crystallised oxalic acid.                                            [Ki
50     „    (63 c.c.) methyl alcohol.                                            ^j''
f?^ j
The oxalic acid is ])owdered and healed in a. basin on a water-
bath, which is kept, boiling briskly, until no more water is given off                    1W
(one to two hours).    It must be occasionally stirred and powdered                       *j! j>
up.    It is then heated to 1 10    120° in an air-bath or in a Victor                       1A'
Meyer drying apparatus  (see  p.  27)  until  it  loses the  weight                        111
corresponding to two molecules of water.     If the Victor Meyer                    I ^
apparatus is used, amyl alcohol, b. p. 132 , should be placed in
the outer jacket.
The dehydrated and powdered oxalic acid Ls mixed with the
PRACTICAL ORGANIC CHEMISTRY

methyl alcohol, and the mixture heated on the water-bath for
two hours with an upright condenser. The liquid is then distilled.
with a thermometer. When the temperature rises to 100° the
receiver is replaced by a beaker, and the water-jacket of the
condenser removed. The thermometer rises rapidly to the
boiling-point of methyl oxalate, 160 — 165°, and the distillate
solidifies in the receiver. It is drained at the pump and dried.
It may be recrystallised from spirit. Yield, 20—25 grams.

s.— Colourless plates ; m. p. 54° ; b. p. 163°.
Reactions.— ¥m this purpose the alcoholic mother liquor from
the crystals may be used.

1.  Add a little caustic potash solution.    Crystals of potassium
oxalate are deposited.    The ester is hydrolysed.

2.  Add  a few drops  of concentrated  ammonia.     A white
crystalline precipitate of oxamide is formed, C9O.>(OCH3).>-i-

PREPARATION 27.
Glyoxylic Acid, CHO.COOH + H2O.
Glycollic Acid, CH2OH.COOH.
Tafel and Friedrichs, Ber.^ 1904, 37, 3187 ; Centralblatt ; 1905
II, 1699.
20 grms. oxalic acid (in fine powder).
100 c.c. sulphuric acid (10 per cent.).
The process is one of electrolytic reduction and the apparatus.
is similar to that shown in Fig. 77, p. 144. It consists of a smstll
porous cell (8 cm. x 2 cm. diam.) surrounded by a narrow beal<cr
(n cm. x 6 cm. diam.). The oxalic acicl, mixed with 100 c.e.
10 per cent sulphuric acid (titrated against standard baryUt
solution) forms the cathode liquid and is placed in tin-
beaker. The porous cell is filled with the same strength of
sulphuric acid and forms the anode liquid. The electrodes rtrcr
made from ordinary clean sheet lead. The anode consists of ;i
thin strip projecting about two inches from the cell and tlic
GLYOXYLIC ACID

cathode is made from a rectangular piece 10x15 cm. with a
long tongue, the square portion being bent into the form of a
cylinder surrounding the porous cell, and the projecting tongue
serving as attachment to the circuit (see Fig. 77, p. 144). It is
advisable to reverse the current before use so as to produce a
metallic surface.
The whole apparatus is placed in a good freezing mixture.
The electrodes are connected in circuit with an ammeter and
resistance as described on p. 144. The reduction requires theoreti-
cally 9 ampere-hours and the strength of current may vary
between moderately wide limits (2—6 amperes) per 100 sq. cm.
of cathode surface. The cathode liquid should be frequently
stirred so as to bring the suspended ^oxalic acid into solution,
and, as the yield of glyoxylic acid depends on efficient cooling,
it is important that the temperature should not exceed 10°. If
the temperature is allowed to rise, glycollic acid is formed.
The glyoxylic acid is separated as the calcium salt. The
cathode liquid is poured into a basin and the sulphuric and
unchanged oxalic acid precipitated with standard baryta solution.
The mixture is filtered and the nitrate is concentrated in vactio
at 60° (see p. 94), neutralised in the cold with calcium
carbonate, boiled up for a short time and filtered. As calcium
glyoxylate is only slightly soluble in cold water (i part in 140
of water at i8c) the greater portion crystallises on cooling. If
calcium glycollate, which is much more soluble, is present, it
may be separated from the filtrate by concentrating the solu-
tion on the water-bath and precipitating with spirit. To obtain
free glyoxylic acid, the calcium salt is dried and suspended
in water, the calculated quantity of oxalic acid added and the
mixture filtered. The filtrate is evaporated in a vacuum
desiccator, when the glyoxylic acid remains as a viscid liquid
which may crystallise on long standing,
COOH.COOH 4- H2 = CHO'COOH + H2O.
Properties.—Crystallises in rhombic prisms ; very soluble in
water.
Reactions,—i. Adda few drops of the acid solution or solu-
tion of the calcium salt to a few c.c. of ammonia-silver nitrate
and warm in hot water. A silver mirror is deposited.
2. To the acid, neutralised with potassium carbonate, or to the
104

PRACTICAL ORGANIC CHEMISTRY

solution of the calcium salt, add a solution of phenylhydrazine
acetate and a little sodium acetate. The -phenylhydrazoiie
separates on standing in minute yellow crystals, which can
recrystallised from alcohol. The neutral salts also
with sodium bisulphite and hydroxylamine.
G-lycollic Acid. If it is required to convert the oxalic acid
completely into glycollic acid, the same method is employee! as
described above, but the temperature is raised to 35° and the
number of ampere-hours is doubled. The separation is effected
as the calcium salt and precipitated with alcohol as already
described.
COOH.COOH + 2H2 = CH2OH + COOH + H2O
Properties.—Crystals m. p. 79—80° ; very soluble in water.
The air-dried calcium salt contains three molecules of water of
crystallisation and is soluble in So parts of water 15°, and in 19
parts at 100°. See Appendix^ p. 258.
PREPARATION 28.
Palmitic Acid, C15H31CO.OH.
Fremy, Annalen, 1840, 36, 44.
30 grins, palm oil.
24     „    caustic potash.
The caustic potash is dissolved in its own weight of water,
The palm oil is melted in a large basin on the water-bat! i,
and the potash solution added with constant stirring. THt;
mixture is heated for half an hour. Half a litre of boiling
water is poured in, and, after stirring well, 75 c.c. concentrated
hydrochloric acid are gradually added, and the heating" con-
tinued until the palmitic acid separates out as a transparent
brown oil on the surface of the liquid. It is allowed to cool, arid
the cake of impure acid removed and pressed between filter-
paper. The acid is now melted in a small basin on the water-
bath and decanted, from any water which may have separated,
into a retort (250 c.c.). It must be distilled in vacuo. TTie
neck of the retort is fixed into a small filtering tube, which servc-n
as receiver, as shown in Fig. 67. A few small pieces of ung^lazcd
PALMITIC ACID

105

pot are dropped into the retort, the tubulus of which is closed
with a cork holding a thermometer. Before commencing the
distillation the apparatus should be tested to see that it is air-
tight. It [Lis then evacuated with the water pump (See Fig. 35,
p. 44), and the distillation commenced.
During the distillation it is advisable
to hold the Bunsen and to heat the
retort with the bare flame. Under a
pressure of 36 mm. the acid distils at
245°. The pale yellow oil which col-
lects in the receiver is poured out
into a basin whilst hot and allowed to
cool. The cake of acid is spread on
a porous plate and left to drain,
when it becomes nearly colourless,
and, after one or two crystallisations

from   small   quantities  of   spirit, is  pure,   and  melts at 62°.
Yield about 20 grams.

The aqueous portion from which the cake of acid is removed
contains free hydrochloric acid, potassium chloride, andglycerol.
The latter may be obtained by evaporating to dryness on the
water-bath, and extracting the residue with small quantities of
alcohol, which dissolves out the glycerol. On evaporating the
alcohol impure glycerol is left.

FIG. 67.

CH2.O.CO,C15H31

CH.O.COCnH3l +
I
CI-L,O.CO,C15H3l

Palm i tin.

3C16HS1COOK + C3>H6(OH)3

Potassium palmhate.         Glycerol.

C16H31COOK + HC1 = C15H31COOH + KC1.
Properties.—Crystallises in tufts of colourless needles ; m. p.
62° ; soluble in alcohol and ether ; insoluble in water.
Reactions.—i. Dissolve a small quantity of the acid in caustic
soda solution and add salt. Sodium palmitate separates as a
curdy white precipitate.
2. Boil another portion of the acid with caustic soda and let it
cool Pour off the liquid from the crust of sodium palmi-
tate, which forms on the surface, wash once or twice with
106               PRACTICAL ORGANIC CHEMISTRY     \
a little cold water, and dissolve the sodium salt in hot
water. On cooling, a thick gelatinous mass of sodium
palmitate separates. See Appendix, p. 258.
Glycerol (Glycerin), CHS(OH).CH(OH).CH2(OH)
Scheele, Opusc^ 1779, 2, 175.
Glycerol is obtained by the hydrolysis of fats and oils, and
purified by distillation under reduced pressure with superheated
steam.
Properties.—A viscid, colourless liquid, with a sweet taste; m.'p.
17°, b. p. 290°. It boils, under ordinary pressure, with partial
decomposition forming acrolein ; sp. gr. 1*269 at I2° J miscible
with water and alcohol ; insoluble in ether and the hydrocarbons.
Reactions.—i. Heat a few drops of glycerol with some powdered
potassium hydrogen sulphate. The irritating smell of acrolein
is at once perceptible.
2. Make a borax bead and dip it into a solution of glycerol
and bring it into the flame. A green colouration due to boric
acid is produced.
PREPARATION 29.
Formic Acid, H.CO.OH.
Berthelot, Ann. Chim. P/iys.,ri&$6, (3) 46, 477 ; Lovin, Bull.
Soc. Chim., 1866, (2) 5, 7 ; 1870, (2) 14, 367.
50 gnns. anhydrous glycerol.
200     „     oxalic acid (in four portions of 50 grams).
The glycerol is dehydrated by heating it gently in a basin on
a sand-bath until a thermometer with the bulb immersed in the
liquid indicates 175°. Fifty grams of commercial crystallised
oxalic acid and 50 grams of glycerol are heated in a retort
(250 c.c.) over wire-gauze, with condenser and receiver. A
thermometer is fixed through the tubulus with the bulb in the
liquid. The reaction begins at about 80°, and at 90° proceeds
briskly, carbon.dioxide being evolved. The temperature is main-
tained at 105 —110° until the evolution of gas has slackened.
Some aqueous formic acid has meanwhile collected in the
FORMIC ACID

107

receiver. The contents of the retort are now cooled to
about 8oc and a further 50 grams of oxalic acid added. The
reaction recommences on heating with the formation of aqueous
formic acid, which becomes more concentrated with each fresh
addition of oxalic acid until the distillate eventually contains 56
per cent, of acid. The other portions of oxalic acid are added
in the same way. In order to regain the formic acid which
remains as monoformin in the retort, the contents are trans-
ferred to a round flask, diluted with about 250 c.c. of water
and distilled in steam, until the distillate has only a faintly acid
reaction (about 250 c.c.).

Distillation in Steam.—The apparatus for distilling in
steam is shown in Fig. 68.    A large flask, or, preferably, a i gallon

FIG. 68.
tin is closed by a double bored cork. A safety-tube passes
through one hole, and a bent tube which terminates below the
cork passes through the second hole, and is attached by rubber
tubing to the inlet-tube of the distilling flask (i litre). The
flask is sloped to prevent the contents being splashed over
into the condenser. It is heated on the sand-bath or asbestos
board to boiling, and steam passed in. The united distillates
are poured into a basin and neutralised by adding lead car-
bonate until, on heating, no further effervescence occurs. The
liquid is now left for a moment to settle, and the clear solution
decanted, whilst hot, through a fluted filter. The residue in the
PRACTICAL ORGANIC CHEMISTRY

basin is boiled up again with a volume of water equal to that
decanted, and again a third and fourth time, and filtered hot
each time until no more lead formate is dissolved. Xlae U»;id
formate will have now passed into solution and the liquid is then
evaporated down on a sand-bath of i~inK-
burner(see Fig. 69), until crystals £iplK*ar
on the surface, when the liquid is pu*- on
one side to cool. Lead formate crys*a*~
lises out in long white needles. Vit:ld
about 150 grams. In order to ototuin
pure formic acid, hydrogen sulpliW0 *s
passed over the heated lead salt. It **
carried out as follows : —
9'                The powdered salt, dried on the w*ttor-

bath, is introduced in a long layer into a sloping wide tulxs
loosely stopped at the lower end by a plug of glass wool or
asbestos.* To the lower end of the tube a receiver, in tine form
of a distilling-flask, is attached, which is protected from moisture
by a drying-tube. The salt is heated gently by moving SL fhune
along the tube whilst hydrogen sulphide, washed throug'li wnt or,
and dried by passing through a U-tube containing calcium chlor-
ide, is led over the salt in not too rapid a stream. Tlie 3<-»;nI
formate blackens, and is slowly converted into lead sulplilcle ;md
formic acid, which drops into the receiver. The acid, which retri I ns
a strong smell of hydrogen sulphide, is freed from the latter l>y
distillation over a little dry lead formate. Yield is iiearly
theoretical.

C.,H5(OH)3+C2H304=C3H5g)JI^H+CO:!+H;iO.

Glycerole monoformin.

Formic acid.
/^j.— Colourless liquid, with a penetrating smell i*c*-
sembling sulphurous acid; b. p. 100°; sp.gr. 1-223 at o°; solidifies
below o° to colourless crystals; m. p. 8'6° ; soluble in water ;incl
alcohol.
Reactions.— Tor the following tests use a neutral solutiori   j >»•<*-
pared as follows :—Boil a little lead formate with a solution   of
ALLYL ALCOHOL                               109

sodium carbonate, filter, add a slight excess of nitric acid, boil a
minute, add dilute ammonia and boil until neutral, i. Aclcl
a drop of ferric chloride. A red colouration is produced,
which, on boiling, becomes turbid from the formation-of basic
ferric formate. (Compare acetic acid, p. 74.)
2.  Add to the solution a few drops of a  solution of silver
nitrate and warm.   Metallic silver is deposited as a black powder.
3.  Add to the solution a few drops of a solution of mercuric
chloride and. warm.    White mercurous chloride is deposited.
4.  Add concentrated  sulphuric acid to a little formic acid,
solid lead formate, or other salt and heat.    Carbon monoxide
is evolved, and may be lighted at the mouth of the test-tube.
(HCOO),l)b+H,SO.l^PbSO.14-2l-LO-h2CO.     See  Appendix..
p. 259.
PkKPAKATION  30.
Allyl Alcohol, CH,:CILCILOH.
Tollcns, Hcnninger, Annalen, 1870, 156, 129.
50   gnus, oxalic acid.
200      „     glycerol.
,|-    „     ammonium chloride.
A mixture of the above substances is heated in a retort
(o litre) over wire-gauze with condenser and receiver.* A rapid
evolution of carbon dioxide at first occurs, and the temperature,
indicated by a thermometer dipping* into the liquid, remains for
some time stationary at about 130". As the temperature slowly
rises the evolution of gas slackens, and after a time (at about
i8oc) entirely ceases. When the temperature has reached 195°
the receiver, which contains aqueous formic acid, is changed.
At 200—210° carbon dioxide is again given off, and oily streaks
are observed to run clown the neck of the retort; at the same
time a disagreeable penetrating smell is perceptible. By gently
heating the contents of the retort, a temperature of 220—230° is
maintained for some time, and when it has finally risen to 260°
the distillation is slopped. The distillate is a mixture of allyl
alcohol and water, and there is also present allyl formate,
glycerol, and acrolein. Excess of glycerol remains in the
retort and may be used again by repeating the operation with a
smaller quantity of oxalic acid (30—40 grams) until the residue is
no              PRACTICAL ORGANIC CHEMISTRV

too small or has become dark-coloured and thick. The distil-
late is submitted to a second distillation, which is continued
until no oily layer separates from the latter portions which distil
on treating with solid potassium carbonate. This occurs when
the temperature reaches about 105°. On adding solid potassium
carbonate to the distillate, the allyl alcohol settles out as an oil.
This is separated and distilled. Yield about 15 grams boiling
at 92—96°.

C2H2O4 + C3H8O3= C3H5(OH)2.O.CO.H + H,

Glycerol monoformin.

Allyl alcohol.
Properties. — Colourless liquid, with a pungent odour ; b. p.
9^*5°; sp. gr. 0-858 at 15°.
Reaction. — Add bromine water to a little of the allyl alcohol.
It is immediately decolourised, C3H6OH + Br3==C3H6BraOH.
See Appendix^ p. 259.
PREPARATION 31.
|   •   •                                                  Isopropyl Iodide, CH3.CHI.CH3
;      !_                                                Markownikoff, Annalen, 1866, 138, 364.
!      '   >                 .                                             60 grms. iodine.
'                                                                 40     „     glycerol.
\                                                                                  32     „     water.
!,                                                                        1 1     „     yellow phosphorus.
The iodine, glycerol, and water are placed together- in a retort
(250 c.c.), standing over wire-gauze and attached to a condenser
1 1    ,                           and receiver.    The phosphorus is cut up under a layer of water
i, "      ,                         into small pieces, the size of a pea, and, with crucible tongs,
.    ,f   J                          dropped gradually into the  retort.    The  introduction  of the
j'{ v \                          phosphorus generally produces at the beginning a violent re-
f, W     , ',                 t         action, often accompanied by a  vivid  flash.    If.no reaction
^ ' lt« !IN'                         occurs on adding the first few pieces of phosphorus, the retort
{           •   T' .                          must be warmed gently.    The last two-thirds of the phosphorus
i      !     ',   . '                         may be added more quickly.    The contents of the retort are
4 * ,                          now distilled as long as any oily liquid passes over.    The distil-
i"*l> *                                       *ate ^s P°ured bac^ mto ^e retort and redistilled.    The liquid-
I  * .   ' [' J 'I                            is then shaken up with dilute caustic soda solution in a separating-
EPICHLORHYDRIN

funnel, the isopropyl iodide separated, dried over calcium
chloride, poured off and fractionated in a distilling- flask. It
distils entirely at 88—89°. Yield 30—35 grams.

-2.       CH2OH                CHJ

CHOH + 3HI = CHI + 3H20

CH2OH
	CHJ
 Propenyl triiodide.

CH2I
 CHI +2HI I
	CH3
 = CHI + 2l2
 i

CHoI
	CH3
 Isopropyl iodide.

Propenyl triiodide is probably formed as an intermediate pro-
duct, though it does not exist in the free state.
Properties.—^Colourless liquid ; b. p. 89*5°; sp. gr. 1744 at o°.
See Appendix•, p, 260.
PREPARATION 32.
CH2C1.CH.CH2
Bpichlorhydrin,        "      \O/"
Reboul, Annalen^ SpL, 1861,1, 221.
200 grms. glycerol.
160 c.c.     glacial acetic acid.
The glycerol, which must be dehydrated (see p. 106), is mixed
with an equal volume of glacial acetic acid. Hydrochloric acid
gas (see Fig. 65, p. 93) is passed into the cold liquid for about
two hours, when it ceases to be absorbed. The mixture is now
heated on the water-bath, and, after standing twenty-four hours,
the current of gas is continued for about six hours more. The
liquid is distilled with a thermometer.* Hydrochloric acid is
first given off, together with acetic acid. As the temperature
rises, the dichlorhydrin and acetodichlorhydrin distil. The
portion distilling at 160—210°, consisting mainly of dichlorhydrin,
is collected separately and used for the preparation of epichlor-
PRACTICAL ORGANIC CHEMISTRY

hydrin. Yield of dichlorhydrin about 120 grams. Epichlor-
hydrin is obtained by the action of aqueous potash solution
upon the dichlorhydrin. A solution of 100 grams of caustic
potash in 200 c.c. of water is well cooled and poured slowly, with
constant stirring, into the dichlorhydrin. Rise of temperature
must be carefully avoided. The epichlorhydrin is separated
from the product by adding ether, which dissolves out the
epichlorhydrin. The upper layer is separated, shaken up
with a little water, and again separated. It is then dehydrated
over calcium chloride and decanted into a round flask. The
ether is first removed on the water-bath. The residue is then
fractionally distilled. This is effected by attaching a fractionat-
ing column to the flask (see p. 137). The portion boiling
at 115 — 125° is epichlorhydrin, and is collected separately. The
portion boiling above this temperature consists mainly or
acetodichlorhydrin. Yield 25 — 30 grams.

CH2OH.CI-IOII.CHoOH + HC1 = CH2C1.CHOH.CH2OH + H20.

a-Monochlorhydrin.

CH2CLCHOH.CH2OH + HC1 = CH2C1.CHOH.CH2C1 + H20.

aa-Dichlorhydrin.

CH2Cl.CHOH.CH2Ci + KOH = CHCKLCHoCl + KC1 + H20.

Epichlorhydrin.
Properties. — Mobile liquid, with an ethereal smell ; b. p.
117°; sp. gr. 1-203 at o°.
Reaction. — Warm a little of the epichlorhydrin with caustic
potash solution. It dissolves, forming glycerol. See Appendix^
p. 260.
CH(OH).COOH
Malic Acid,   |
CH2.COOH
Malic acid is prepared from the juice of the mountain ash
berries by precipitation as the calcium salt.
Properties. — It is soluble in water and alcohol, but not in
ether. On heating, it loses water and is converted into fumaric
and maleic acids (see p. 125). On oxidation it gives malonic acid
and on redaction succinic acid.
Reactions. — r. Make a strong neutral solution, add calcium
chloride solution and boil. The calcium salt is precipitated.
SUCCINIC ACID

2. Mix about 0*5 gram each of powdered malic acid and
resorcinol, and add r c.c. of concentrated sulphuric acid.
Warm the mixture for a moment over the llame until it
begins to froth. On cooling and adding water and caustic soda,
solution, an intense blue fluorescence is produced (von Peehmann).

PUKPA RATION   33.

Succillic Acid (Kthylenedicarboxylic Acid),

C(K)H.CII,j.CHa.COOIl".
Schmitt, Aiuialen, 1800, 114,   100.
10 grins, malic acid.
30     „      hydriodic acid.
2     ,,      red phosphorus.

The hydriodic acid is conveniently prepared, according to
Gattermann, as follows: —A small round flask (too c.c.) is
provided with a tap-funnel and delivery-tube, the latter being
attached to a U-tube as shown in Fig. 70. The LMube is filled
with broken glass or pot, which
has been coated with amor-
phous phosphorus by rubbing
it in the phosphorus slightly
moistened with water. The
flask Is first detached from the

and funnel, and 44
grams of iodine introduced.*
Four grams of yellow phos-
phorus, cut in small pieces, are
then added. The phosphorus
must be cut under water,
brought on to filter-paper with
crucible tongs, pressed for a moment, and transferred with
tongs to the flask. Each piece of phosphorus as it drops in
produces a flash. When the phosphorus has been added a dark
coloured liquid is obtained, which solidifies on cooling, and
consists of PI;{. The flask, when cold, is closed with its cork,
and the delivery tube from the LMube is inserted loosely into
the neck of a small flask containing 50 c.c. of watei.-, so that
the open end of the delivery-lube is above the surface of the
water. It is kept in position by a wedge of cork fixed in the
COHKN'S ADV. l». O. C.                                                   f
IT"

I -

114              PRACTICAL ORGANIC CHEMISTRY

neck. Ten c.c. of water are now added gradually from the tap-
funnel.    Hyclrioclic acid is evolved, and, after being freed from
iodine in the LJ-tllke> 'ls absorbed by the water. When the water
has been added, the liquid is gently heated over a small flame
until no more fumes issue from the delivery-tube.    The aqueous
solution of hydriodic acid is distilled with a thermometer, and
the portion boiling at 125° and above is collected separately.    It
consists [of strong hydriodic acid .solution,  containing  about
57  per cent,   of HI.    The   malic  acid  is   dissolved   in   the
hydriodic   acid    and   poured   into   a   stout-walled   tube   for
sealing.    The red phosphorus is added, and the tube sealed      \
in the usual way (see p. 24).    It is heated in the tube-furnace
for six hours at 120°.    On removing the tube it is found to be
filled with  crystals of succinic acid mixed with  iodine.   The     {*
contents are poured into a basin and evaporated to dryness on     >v
the water-bath.    The residue, when cold, is stirred with a little
chloroform to dissolve the free iodine, which is then decanted,     *
and the process repeated if necessary.    After warming to drive     {
off the chloroform, the substance is dissolved in hot water and     "
set aside to crystallise. Succinic acid crystallises in long prisms.
Yield 5 grams.
" COOH.CHOH.CHo.COOH + 2HI = COOH.CHo.CHo.COOH
+ H2O 4- I3.
Properties.—Colourless prisms ; m. p. 180°. On distillation,
the acid loses water and is converted into the anhydride.
Reaction.—r. Make a neutral solution by boiling with an
excess of ammonia, and add to one portion, calcium chloride ;
no precipitate is formed ; to another portion add a drop or
two of ferric chloride ; a brown precipitate of ferric succinate
is thrown down. See Appendix, p. 261.
CH(OH).COOH       :
Tartaric Acid (Dihydroxysuccinic Acid), |
CH(OH).COOH
Scheele (1769).                                      |
The acid potassium or calcium tartrates are found in many
plants ; but the chief source of tartaric acid is the impure acid
potassium salt, which separates out as wine-lees, or argol from
grape-juice in process of fermentation.                                        ^
Properties.—The   acid    crystallises   in   monoclinic   prisms,     <
ETHYL TARTRATE

soluble in   alcohol and water, but not in ether.    It turns the
plane of polarisation to the right ; m. p. 167—170°.
A\'trt:tio?js.—i. Heat a crystal of the acid. It gives an odour
resembling burnt sugar. Carefully neutralise a solution of tar-
taric acid with caustic soda, and make the following tests : —
2.  Add calcium chloride and stir with a glass rod.    A crystal-
line precipitate of calcium tartrate, C4H4OGCa + 4H2O,-is formed
which dissolves in acetic acid and caustic alkalis.    Repeat the
foregoing test, but add a few drops of acetic acid before the cal-
cium chloride.    There is no precipitate.    Calcium sulphate also
gives  no  precipitate   with   tartaric   acid  or  neutral tartrates,
(compare reactions for oxalic acid, p. 100).
3.  Add silver nitrate solution.   The white precipitate is the
silver salt.    Add two or three drops of dilute ammonia until the
precipitate is nearly dissolved,   and  place  the  test-tube in a
beaker of hot water.   A silver mirror will be deposited.
4.  Add a few drops of acetic acid and a little ammonium or
potassium  acetate solution to a moderately strong solution of
tartaric acid or a neutral tartrate.    On stirring with a glass rod,
the acid potassium or ammonium tartrate will be precipitated.
5.  To a solution  of tartaric acid or a tartrate in water add
a drop of ferrous sulphate solution and a few drops of hydrogen
peroxide and make alkaline with caustic soda.    A violet colora-
tion is produced (Fenton's reaction).
PREPARATION 34.
CH(OH).CO.OG,HB
Ethyl Tartrate, |
CH(OH).CO.OC2H6.
Anschiitz, Pictct, Bcr., 1880, 13,   1176.
30 gnris. tartaric acid.
160 c.c. absolute alcohol.
The tartaric acid is finely powdered and mixed with half the
above quantity (So c.c.) of absolute alcohol. The mixture is
heated on the water-bath with upright condenser until dissolved.
The flask is immersed in cold water, and the well-cooled
solution saturated with dry hydrochloric acid gas (prepared in
the usual way by dropping cone, sulphuric acid into cone,
hydrochloric acid, see Fig. 65, p. 93). After standing for an
n6             PRACTICAL ORGANIC CHEMISTRY

hour or two (or preferably overnight), the hydrochloric
excess of alcohol and water are expelled by evacuating-
flask and distilling in vacito on the water-bath. The
maining half of the alcohol is added to the residue, and
mixture again saturated in the cold with hydrochloric acid &'**s-
After standing, the acid, alcohol and water are removed <*s
before, and the residue fractionated from an oil or metal batli in
vacua. The ethyl tartrate distils as a clear viscid liquid. After
a second distillation in vacua the substance is pure.
At ii mm. it boils at 155°.
„    20     „       „       „        164°.
The yield is 80 per cent of the theory.    See Appendix, p. ^6 2.
Determination of Rotatory Power.—The rotatory power
of ethyl tartrate, which is an optically active substance, is
determined by means of a polarimeter. One of these instru-
ments known-as Laurent's polarimeter is shown in Ifi&s.
71 and 72.
The monochromatic light of a sodium flame is used in these
determinations and is obtained by  suspending  in a  Bun sen
flame a platinum wire basket containing fused sodium chloride
or the more volatile bromide.    The latter gives.a brighter flmnc,
but the basket requires replenishing more  frequently.        The
light from the flame passes  through  a  cell  B,  containing    a
solution of potassium bichromate (or a crystal of this substixri <'*<•')i
which deprives it of blue or violet rays.    It then passes thi-ough
the polarising nicol prism P.   A plate of quartz cut parallel    to
the optic axis covers half the opening D, and is of such a   t "hick-
ness that it produces a difference of a half-wave length   (or   an ,
exact odd multiple of a half-wave length) between the two    r*iys, ;
which it gives by double refraction.    The light then    passes .<
through the substance placed in the tube T and entering-   a.t  K f
strikes the analysing nicol N.    The telescope OH  is focus set I cm
the edge of the quartz plate at D.    When N is turned, a pointer
moves over the graduated circle C and its position can be    read |
by means of the lens L.                                                                  )
The Theory of the Instrument may be explained   as <
follows :—If, after passing through the nicol P, the plant*   of
vibration is in the direction OB, Fig. 73 a, then in the half of   the \
field to the right, uncovered by the quartz plate, it passes on  un- f
nS

PRACTICAL  ORGANIC  CHEMISTRY

changed. When it strikes the quartz the ray is broken up i
the two components oy and Ox. These traverse the quartz
with different velocities, and since one ray is retarded half **•
wave-length in respect of the other, the vibration of one com-
ponent will be represented by oy, but the other must be i*e-
presented by Ox' instead of Ox. These two combine ojl
emerging to a plane polarised ray vibrating in the direction
OB' so that the angle AOB' is equal to the angle AOB.

If now (the tube containing water or other non-rotating
liquid) the nicol N be so placed that it is parallel to nicol 1%
then the light, in the half of the field to the right, will pass
through unchanged, but only a portion of the light which. l^^iS

FIG. 73
passed through the quartz diaphragm with its plane of vibration
in the direction OB', will pass through N ancl consequently trie re
will be different intensities of illumination in the two halves*
of the field, Fig. 73 b (if the angle a is 45° then the angle ISO I*
will be 90°, and the light in the left half of the field will be com-
pletely obscured). Similarly if the plane of the nicol N be rnncle
parallel to OB'there will be a greater intensity of illumination
in the left half of the field, Fig. 73 c. Between the two positions
of the nicol N there must necessarily be one which gfives
uniform illumination of the whole field, and this is the 2:0ro
point of the instrument, Fig 73 d.
If the tube T, containing the active substance, be interposed
between the two nicols, then both rays OB and OB' will "be
rotated through equal angles, and to re-establish uniform
MOLKCULAk   ROTATION                       119

illumination in the two halves of the field, the nieol N must
be turned through an angle equal to the angle of rotation, which
is then measured on the divided circle.

When the angle « is small, i.e. when the plane of
vibration of the polarised light is almost parallel to the optic
axis of the quartz, the greatest degree of sensitiveness is
attained, for then a very small change in the position of N
causes a great difference in the respective illuminations in the
two halves of the field. As « increases, the sensitiveness
diminishes, but a greater total intensity of illumination is ob-
tained. By moving j (Fig. 71) the position of the nicol p may
be altered. For clear colourless liquids the angle a may be
made comparatively small ; but in the case of coloured liquids
it is necessary to have a larger, and so obtain a greater intensity
of light at the cost of sensitiveness.

Calculation of Results ; Homogeneous Liquids.-
The angle of rotation, represented by «i> (for sodium light), varies
with the length of the column of substance through which the
light passes. One decimetre has been chosen as unit of length.
The angle also varies with the temperature, which must conse-
quently be determined for each observation.

For the comparison of the rotary power of different substances,
use is made of the constant specific rottition, which may be defined
as the angle of rotation, produced by I gram of active substance
in I c.c. by a layer I dm. in length. This is obtained by dividing
the observed angle of rotation by the product of the length in
decimetres, and the density of the substance at the temperature
at which the observation was made.

Molecular Rotation is the above quantity multiplied by
the molecular weight M of the compound, and divided by 100 to
avoid unwieldy numbers, and is represented thus .........

.
100
It expresses the angle of rotation of i mm. of active substance
containing i gram-molecule in i c.c.
120

PRACTICAL  ORGANIC  CHEMISTRY

Eotation of Ethyl Tartrate.—Fill a 200 mm. pohrimeter-
tube with the tartrate prepared. Whilst it is settling determine
the zero of the instrument, and if it does not coincide with tlie
zero of the graduated circle, a corresponding correction must l>e
introduced in the subsequent observations. The tube is then
placed in the instrument, and the angle of rotation determined
by turning the analyser N until equality of illumination is esUtl>~
lished in the two halves of the field. In making polarimet ric:
observations reliance should not be placed on a single setting °f
the instrument, but at least five or six readings should be ma.de,
which, with a good instrument, should not differ by more tli.m
four or five minutes. The temperature at the time of observa-
tion must be noted, and the density determined cither at lliiit
temperature or at two or three, other temperatures, and tlie
required density found by extrapolation,

Example :—

Temp.
		•    Length.
			a
	,/ i -2059
	[a],,
 7*66

2O°
	
	
	199*85 mm.
		18° 28'
		
[«]£ = 7'66° [a]}? - 7-47° [a]g = 7-27°
				- Anschiitz, Pictet, /Av., 1880, 13, 1177.
 }
			

	L«lb4
 Mb8
 MS
		= 7-07 = 6-86° = 6-66°
	/•   By extrapolation.
			
Eotation of Tartaric Acid.—The specific rotation of a
dissolved substance can be calculated from the rotation of tlit;
solution if the concentration is known. The formula to be u.*>tMi
for this purpose is :—

where a is the angle of rotation of solution, / the length of 11 it!
tube, and c the concentration, i.e., the weight in grams of tlie
dissolved substance contained in 100 c.c. of solution. "I'll ft

dissolved  substance  contained

formula [a]D = A^£ may also 1
Ip a

where p is the percentage (by weight) of substance in solution,

formula [a]o = •.-—- may also be used (it is, in fact, identic.11 j,
Ip a
ROTATION   OF TARTARIC ACID

and /'/the density of the solution. The specific rotation of dis-
solved substances varies with the concentration and with the
temperature.

Heat some tartaric acid in an air-bath to 110°, until it is quite
dry. Weitfh accurately about 20 grams of the dry acid and
dissolve in water ; then make up the solution to exactly 100 c.c.
Determine the rotation of the solution in a 200 mm. tube, and
note the temperature at which the observation is made.

Take 50 c.c. of the solution and dilute it to 100 c.c. Deter-
mine the rotation of this solution tif ///<• same fcmpcmhtrc as
that at which the first rotation was observed.

Dilute' 50 c.c. of the second solution to 100 c.c., and a^ain
determine the rotation at the same temperature.

The same process can be repeated once or twice more. Cal-
culate the specific rotation of the tartaric. acid, usinjj the Iirst
formula. Plot the results on squared paper, making the ordi-
nates specific rotation and the abscissae concentration.

Example :—

Temp.

IO

10"
10"

Concentration.

40
2O
IO

Length of tube.

Auyjc of Rotation.
	Spec. Rut. '^'"

6"
	•!-   7*5"

3° 59'
	•I   <r<K>"

2"  II'
	•i 10-91"

(Krcckc, />V.v.•//«.'//,' ,SWmv//<v///V, p. :•-.•;•;.)

The following table shows the influences of temperalinv on
the specific rotation of an aqueous sululion containing 20 grains
of tartaric acid in roo c.c.

o

10"
20°

40°
60°

So0

100°


	K,,,:,,i,,
	Sprrilir 1
	„,„!„„.

3
	2,X'
	•!    S
	oO"

3
	5<i'
	-1   o
	()(>''

4"
	?<v*'
	1   II
	57"

5"
	2S'
	-1 rj
	00"

<r
	2S'
	-1 lO
	10"

7"
	2l'
	•( iS
	3^

8°
	*<>'
	1 21
	50'

(Thoniscn,,/. prakt. Ck, (a) r-', an.)
122                PRACTICAL ORGANIC CHEMISTRY
PREPARATION 35
Bacemic Acid and Mesotartaric Acid.
CH(OH).COOH
I                       + H,,0
CH(OH).COOH
Pasteur, Ann. Chim. Phys., 1848, (3)24, 442 ; 1850, (3) 28,
Dessaignes, Bull Sec. Chim., 1863, 5, 35^ ; Jungfleisch,
Soc. Chim., 1872,18, 201 ; Hollemann, Rcc. trav. chim. Pays-J&ttft
1898,17,66.                     ^
100 grms. tartaric acid.
350    „    caustic soda (in 700 c.c. water).
Boil the tartaric acid and caustic soda solution for three hours
in a round flask (i litre), or preferably in a tin bottle furnished with
reflux condenser. The use of a tin vessel obviates certain diffi-
culties of filtration which the solution of the silica by the action
of the alkali on the glass entails. The liquid, after boiling", is
carefully neutralised with cone, hydrochloric acid (it is advis-
able to remove a little of the solution beforehand in case of
overshooting the mark) and an excess of calcium chloride solu-
tion is added to the hot liquid. The mixture is left overrun llt»
and the calcium salts filtered off at the pump, washed with
water, and well pressed.
The calcium salts are well dried on the water-bath, or a frac-
tion of the whole weight of the moist salts is taken and dritnl,
and.the total dry weight estimated. The substance is then sus-
pended in boiling water and the calculated quantity of sulplivtric
acid added, after which the mixture is boiled for an hour. 1*h<;
calcium sulphate is removed by filtration, well washed with liot
water, and the precipitate pressed down. The filtrate is concron-
trated on the water-bath until crystallisation begins. Raceuxk
acid crystallises first, and after dehydrating on the water-1:>utli
melts at 505°. A further quantity is obtained on evaporation.
Yield 50—60 grains.
The last mother liquors contain mesotartaric acid, m. p. 1.4 •$ •
144°, which is much more soluble in water than raccmic a.<:Id
To obtain a pure specimen repeated crystallisation is necessary,
RACEMIC ACID AND MESOTARTARIC ACID        133

The yield varies with the period of boiling, but usually does not
exceed 10 grams.

Resolution of Racemic Acid,—The racemic acid is dis-
solved in water (250 c.c.) and divided into two equal volumes.
Half of the solution is carefully neutralised with caustic soda
and the other half with ammonia, and the two solutions then
mixed.

The liquid is concentrated and poured into a crystallising dish.
If, on cooling, the crystals are small and massed together, the
solution has been too concentrated, and must be diluted so that
small, well-defined crystals deposit. A dozen or so of these are

FIG. 74.

picked out, dried, and put on one side. The remaining crystals
are re-dissolved and left to cool in a room of fairly even tempera-
ture.

When the solution is just cold the crystals, previously re-
moved, are sown evenly over the bottom of the dish at distances
of i—2 cms. apart and left for two days. The crystals will have
now grown to a size which will enable the facets to be readily
recognised. Each crystal is dried and carefully examined with
a pocket lens in order to determine the position of the hemi-
hedral facets, and placed in separate heaps. These facets lie
to the right or left hand of the central prism face, as shown in
Fig. 74. The crystals should be weighed, dissolved, and the
solution diluted and examined in the polarimeter. The specific
rotation may then be calculated. See Appendix, p. 264.

41
124               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 36.
Pyruvic Acid, CH3.CO.CO.OH.
Doebner, Annalcn, 1887-, 242, 268.
200 grms. potassium hydrogen sulphate.
100      „    tartaric acid.
The potassium hydrogen sulphate and tartaric acid must toe
finely powdered and intimately mixed. The mixture is distilled
in a round flask (i litre), attached to a moderately long condenser
tube, from a paraffin bath heated to 220*.* The mass at first
froths up, and it is necessary to interrupt the heating when tlie
flask is not more than half full of froth, as otherwise it mny
boil over. When the temperature of the bath has fallen to
about I2OC, the heating may be recommenced. The distillation
is carried on until no more liquid distils. The distillate, whicli
consists of water and pyruvic acid, and has a yellow colour, is
fractionated in vacuo. It is collected at 68—70° at a pressure
of 20 mm., and is quite colourless. Yield 15—20 grams. It
may be fractionated at the ordinary pressure, but is difficult to
obtain colourless in this way.
CO.OH.CHOH.CHOH.COOH = CH3.CO.COOH + CO2 + H2O
Properties.—Colourless liquid; b. p. 165° at atmospheric:
pressure ; m. p. 10—11°; polymerises on keeping.
Reaction.—Dissolve a drop of phenylhydrazine in two drops
of glacial acetic acid, dilute with about i c.c. of water, and acid
a drop of pyruvic acid. A yellow crystalline precipitate of tlie
phenylhydrazone, CH3.C:(N.NH.C0H6).CO.OH, is formed.
CH2.COOH
Citric Acid, C(OH).COOH + H2O  *•
CH2.COOH
Scheele (1784).
Citric acid occurs in the free state, as well as in the form, of
the calcium and potassium salts, associated with malic and ta.r-
CITRACONIC AND MKS AGONIC ACID             125

taric acid, in many plants. It is prepared principally from
lemon juice, from \vhich it. is precipitated as the calcium salt on
boiling with chalk and also l>y the citric fermentation of
glucose.

Properties.—The acid, which contains I molecule of water,
crystallises in prisms ; soluble in water, alcohol, and also mo-
derately soluble in ether ; m. p. 100°. The anhydrous acid melts

at 153—154°.                     .              '

Reactions.— i. Meat a little of the acid and notice the irri-
tating vapours.

Make a neutral solution of sodium citrate by adding caustic
soda to a solution of the acid.

2.  Add lime water. There is no precipitate of the calcium salt,
(C(.JIrp7)Xa.{4-4H/>, until the solution is boiled.

3.  Add calcium chloride solution and boil, and, to another
portion, silver nitrate solution.     Note the results and compare
the reactions with those of tartaric acid (p. 115),

PREPARATION 37.
Citraconic and Mesaconic Acid.
(Methyl fumarlc and Methyl maleic acid).
CH3.C(COOH):CH(COOL1).
Kekule, Lchrbiich, 2, 319; Kittig, Anualcn^ 1877, 188, 73.
250 grms. citric acid (crystallised).
Heat the crystallised citric acid, without powdering, in a porce-
lain basin to a temperature not exceeding 150°. The water of
crystallisation is expelled, and the crystals become pasty and
then fluid. When cold, the solid mass is removed from the
basin by gently wanning, and is coarsely powdered. The anhy-
drous acid is rapidly distilled in portions of 100 grams, from a
retort (250 c.c.) with bent neck (sec Fig. 19, p. 22), fitted to a con-
denser, the receiver being a separating funnel. The distillate
consists of two layers. The lower layer of impure citraconic
anhydride is run off, and. the upper layer, consisting of water and
citraconic acid, is fractionated, the portion distilling at 190—210°
being collected and mixed with the previous lower layer.
I26              PRACTICAL ORGANIC CHEMISTRY

The citraconic anhydride is now distilled in vacua and col-
lected at 110—114° under a pressure of 30 mm. Yield 30 — 35
grams.

CH2.COOH             CH3

C(OH).COOH   =    C.CO\            + COo + 2H9O.

!                         II       \o            -

CH,.COOH              CH.CO/

Properties.— Colourless liquid; b. p. 213 — 214° (ordinary
pressure). To convert the anhydride into citraconic acid the
calculated quantity of water is added (i mol. acid : i mol. water)?
and the mixture well stirred. The whole solidifies, on standing",
to a mass of colourless crystals of citraconic acid, which- are
dried on a porous plate ; m. p. 84— 86°.

MESACONIC ACID. — To a saturated solution of citraconic acicl
in ether (4 parts citraconic acid require about 5 parts of anhy-
drous ether), about I part of chloroform is added, and a few
drops of a moderately strong solution of bromine in chloroform.
The mixture is placed in strong sunlight, when mesaconic acicl,
which is insoluble in ether and chloroform, begins at once to
deposit on the side of the vessel nearest the light. Drops of
bromine are added from time to time until no further precipita-
tion occurs. The pasty mass is then filtered, washed with ether,
and dried on a porous plate. Yield 73 per cent, of the citraconic
acid ; m. p. 202°. See Appendix, p. 265.

PREPARATION 38.
Urea (Carbamide),

Wohler, Pogg. Ann., 1828, 12, 253; Clemm, Annalen,  1848,
66, 382.
50 grms. potassium cyanide (98—99 per cent).
140    „      red oxide of lead.
25     „      ammonium sulphate.
The potassium cyanide is heated in an iron dish over a.
large burner until it begins to fuse, when 140 grains of reel
oxide of lead are gradually added in small quantities and.
stirred in. The heat of the reaction causes the mass to melt
UREA                                     • I27

and froth up. When it fuses quietly, the dark coloured liquid
mass is poured on to an iron pl.tie and allowed to cool.
It solidifies and is powdered and separated from the solid
cake of metallic lead. 200 c.c. of cold water are poured on
to the crude cyanate and, after standing- an hour, filtered
through a fluted filter and washed with a little cold water.
A concentrated solution of 25 grains of ammonium sulphate
is immediately added to the filtrate, which is evaporated to
dryncss on the water-bath, the mass being stirred occa-
sionally to prevent the formation of a surface crust. The
cooled residue is powdered and the urea extracted with alcohol
by boiling on the water-bath, using a reilux condenser and
adding successively small quantities of spirit until the extract
leaves only a small residue on evaporation on a watch-glass.
The greater part of the alcohol is distilled off on the water-
bath, and the residue poured out into a beaker to crystallise.
Yield about 15 grams.

1.              4KCN + Pb,,04 = 4CONK + 3Pb

2.  (NH4)3SO,i + 2CONK - 2CON.NH4 + K>SO4

3.                      CO N. N H4 = C0( N H2)sj

Properties. — Colourless prisms ; in. p. 132°; very soluble in
water ; soluble in hot alcohol.

Reactions. — r. Add to a strong solution of urea in water a
drop of concentrated nitric acid, and to another portion a
concentrated solution of oxalic acid ; the crystalline nitrate
CO(NH3)2HNO., and oxalate (.CO(NH2)2)2CaHaO,, are deposited.

2. Melt a few crystals of urea over a small flame and heat
gently for a minute, so that bubbles of gas arc slowly evolved.
Cool and add a few drops of water, then a drop of copper sul-
phate solution, and finally a few drops of caustic soda. A violet
or pink coloration is produced, depending upon the quantity of
biurct formed.

2CO(NHs)a = N

3. Add a few drops of sodium hypochlorite, or hypobromitc,
to a solution of urea in water. Nitrogen is given off,
CO(NH2)2 + 3NaOCl -"- N2-f-2lIaO H- 3NaCl + CO, (which
dissolves in the alkaline solution).
128                PRACTICAL ORGANIC CHEMISTRY
4.   Add to a solution of urea a few drops of hydro chloric acid
and a solution of sodium nitrite.     Effervescence occurs and
nitrogen and carbon dioxide are evolved.
CO(NH2)2 + 2HO.NO = 2 No + CO2 = 3^2^'
5.   Heat a little urea with soda-lime.    Ammonia is   evolved.
See Appendix, p. 267.
PREPARATION 39.
Thiocarbamide (Thiourea),
Reynolds, Trans. C/iem. Soc., 1869, 22, r ; Volhard, JT. $rakt.
Chem., 1874, (2), 9, 10.
50 grms. ammonium thiocyanate«
The ammonium thiocyanate is melted in a round flask in n
paraffin-bath, and kept at a temperature at which the mass re-
mains just liquid (140—145°) for 5—6 hours. The cooled melt is
powdered and ground with half its weight of cold water, which
dissolves unchanged ammonium thiocyanate, but little of the
thiourea. By dissolving* the residue in a little hot water, pure
thiourea is obtained, on cooling, in colourless, silky needles.
Yield 7—8 grams.
CNS.NH4 = CS(NH2)2.
Properties—Colourless, rhombic prisms (from dilute aqueous
solution), long silky needles (from concentrated solutions) ; m. p.
172°. Very slightly soluble in cold water (i part of thiourea dis-
solves in about n parts of water at the ordinary temperature).
HN—CO
Uric Acid, CO   C—NH
I        |[       >CO
HN—C—NH
Scheele (1776).
Uric acid is a product of the metabolism of trie animal
organism. It is usually prepared from guano, which is treated
first with dilute hydrochloric acid to remove phosphate of cal-
cium. The uric acid is then dissolved out with hot caustic soda
and the clear alkaline solution precipitated with acid.
ALLOXANTIN                                 129
Properties.— Uric acid forms microscopic crystals of a charac-
teristic shape. It is insoluble in water, but dissolves in the
presence of many organic substances. On dry distillation it
yields ammonia, cyanuric acid, and urea.
Reactions.—Evaporate a little of the acid with a few c.c. of
dilute nitric acid to dryness on the water-bath. An orange or
red residue remains. On cooling, add ammonia. A fine purple
colour is produced (murexide test) ; see also Reaction for
alloxan (p. 130).
PREPARATION 40.
Alloxantin, CHH4N4O7 + 3H2O
Liebig, Wohler, Annalen, 1838, 26, 262.
to grins, uric acid.
20   „      (18 c.c.) cone, hydrochloric acid diluted with an
equal weight of water.
i\         potassium chlorate.
The hydrochloric acid is poured over the uric acid. The
mixture is heated to 35°, and the potassium chlorate, finely
powdered, is added in small quantities at a time with constant
shaking. When about two grams of the chlorate have been
added, the uric acid will have nearly dissolved, and the liquid
has a faint yellow colour. It is diluted with double its volume
of water, allowed to stand for about an hour, and filtered. The
filtrate is saturated with hydrogen sulphide, and yields,
after being left for 12 hours, crystalline crusts, often of a
reddish tint, of alloxantin mixed with sulphur. It is filtered
and washed with cold water, and the alloxantin dissolved in a
.small quantity of hot water, and filtered from the residue of
sulphur. On cooling the filtrate, colourless crystals separate
out. Yield 7—8 grams.
CflH4N4O3 + 0 + HoO « C.iH2NaO4 4- CONaH4,
Uric add.                                    Alloxan.                 Urea.
-C.iH.NoO.t 4- H,S = CRH4N4Of + S + H,O,
Alloxaniin.
Properties.— Hard, colourless crystals, slightly soluble in cold4
more readily in hot water.
COHEN'S ADV. p. o. c.                                                  K
130               PRACTICAL ORGANIC CHEMISTRY

Reactions.—i. Add to the solution of alloxantin a little t>a.ryt;L
water ; a violet colouration is produced.

2.  Add ammonio-silver nitrate solution and warm ; rneta,lHc
silver is deposited.

3.   Boil the solution with mercuric oxide ; a violet solution   of
murexide is formed.

PREPARATION 41.
Alloxan (Mesoxalylurea), CONH;CO

Liebig, Wohler, Annalcn, 1838, 26, 256.
5 grms. alloxantin.
5   „      (3*5 c.c.) cone, nitric acid (sp. gr. 1-4).
10   „      (7 c.c.) fuming          „         (sp. gr. 1-5).
The finely powdered alloxantin is added to a mixture of the
strong and fuming nitric acid, and left to stand. Slight evolu-
tion of nitrous fumes occurs, and the alloxantin, which at first
remains at the bottom of the vessel, slowly changes into tin*
more bulky crystals of alloxan, which gradually fill the licjuicl.
The reaction lasts about two days, and is complete wlien a
sample dissolves readily and completely in cold water. "I" IK?
crystalline mass is spread upon a porous plate, thoroughly dried
in the air, and freed from traces of nitric acid by heating in a
basin on the water-bath, until the smell of the acid disappears.
Alloxan may be obtained in large crystals by dissolving' tlie dry
product in the smallest quantity of hot water, and allowing" the
solution to evaporate slowly in a desiccator over sulphuric a.cicL
The crystals are liable to effloresce.
C8H4N407 -!- O - 2C,,H,N,04-
Alloxantin.                         Alluxan.
Properties.— Colourless crystals, containing 4 molecules oi
water of crystallisation.                                                  .
Reactions. — i. A small quantity of the alloxan solution is
evaporated to dryness on the water-bath in a porcelain ~ba.sin.
A reddish residue is left, which turns purple on the addition of
ammonia (murexide). See Appendix, p. 268.
CAKKKINK

PREPARATION 42.

CH...N    CO

I
Caffeine (Trimethyl xanthine),        CO C    N(CI 1,)

CH...N    C-  N ,'yCI1

Digest the tea with 500 c.c. boiling water for a. quarter of an
hour, and filter through cloth into a basin placed over a ring-
burner (see p. 108), so that the liquid in the filter is kept hot.
Moderately line unsized cotton cloth is used, and is wetted and
stretched on a wooden frame as shown in Kig. '/S- Wash with
a further 250 c.c. of boiling water. Add to the. iiltrate a, solu-
tion of basic lead acetate (made by boiling acetate of lead
solution with excess of litharge, and then filtering) until no more

precipitate is formed. Killer hot through a large lluted filter
froiM precipitated albumin, and wash with water. To thr boil •
ing filtrate add dilute sulphuric acid until the le'id is precipitated
as sulphate. Kilter or de-cant from the sulphate of le;ul, and
concentrate the solution with the addition of animal charcoal
to 250 300 c.c. Miter and extract the filtrate three times witb
small quantities (50 c.c.) of chloroform. Distil off the chloro-
form on the water-bath, and dissolve the residue in a. small
quantity of hot water. On allowing (he solution to evaporate
very slowly, long silky needles of caffeine separate, which may
have a slightly yellow tint, in which case they should be drained,
re-dissolved in water, and boiled with the addition of animal
charcoal. The needles contain one molecule of water, which
they lose at 100 and melt at 234*5". Meld about rf; grams.
See Appendix, p. 269.
132                PRACTICAL ORGANIC CHEMISTRY

PREPARATION 43.
/N(CH3).CH2.CO.OH
Creatine.   HN:G/                                -hH2O
Neubauer, Annalen^ 1861, 119, 27.
500 grms. meat.
The meat, separated as far as possible from fat, is put through
a sausage machine, or finely chopped and digested with -J- litre
of water at 50—60°, and well stirred from time to time. It *s
filtered through cloth (see Fig. 75, p. 131), and is then digested
with a further 250 c.c. of water in the same way, filtered, and
the cloth removed from the frame and squeezed out. The
filtrate is heated to boiling to coagulate the albumin, and, on
cooling, filtered. Basic acetate of lead is carefully added, just
sufficient to precipitate the soluble albumin. The liquid, is
again filtered through a fluted filter, and the lead removed with
hydrogen sulphide, which is passed into the warm licjuicl.
The filtrate from the sulphide of lead is concentrated to n thin
syrup on the water-bath and then transferred to a vacuum
desiccator, where it is left over sulphuric acid. In a short time,
especially on the addition of a crystal of creatine, needle-slmpcd
crystals begin to separate, and when no further crystallisation
is observed, the crystals, which have a brown colour., arc
brought on to a porcelain funnel, and washed with a little
spirit. They are recrystallised from a little hot water, with the
addition of animal charcoal. Yield about I gram. The filtrate
from the creatine contains hypoxanthine and sarcolactic acid,
but the small quantity of these two constituents render tliem
difficult to extract
Properties,—Small rhombic prisms ; with difficulty soluble
in cold water, readily soluble in hot water. On warming" \vith
alkalis, it decomposes into urea and sarcosine,
xN(CH3),CH,.COOH
HN:C<          '        "
\STHo
KH(CH3).CR,COONa.
TYROSINE-LEUCINE                            133

PREPARATION 44.
Tyrosine, (OH).C0H4.CH.,.CH(NH,,).COOH
CH3X
Leucine,       ' >CH.CH.,CH(NH,).COOH
CM/
Beyer, Zcit., 1867, 436 ; E. Fischer, Bcr^ 1901, 34, 433,
100 grms. hoof or horn shavings (washed free from dirt).
2 5°    n      Oj6 c.c.) cone, sulphuric acid (in 750 c.c. water).
The shavings and acid are heated in around flask(\\litres) on
the water-bath until the greater part is dissolved, and then hoiled
with reflux condenser over wire-gauze for about 20 hours, until the
solution no longer gives the biuret reaction (p. 127). Add to a
little of the liquid two drops of copper sulphate solution and make
alkaline with caustic soda ; if the colouration is violet or pink
instead of blue, continue to boil. After boiling, the dark
coloured liquid is poured into a large basin and neutralised whilst
hot with slaked lime. The hot liquid is filtered and the residual
calcium sulphate replaced in the basin and extracted twice with
300 c.c. of hot water. The united filtrates are concentrated and
made up to a litre. The total quantity of oxalic acid (about 20
grams) required to precipitate the dissolved calcium salts is
determined by a preliminary estimation with 50 c.c. of the solution.
The liquid is boiled before adding the acid and filtered hot from
the precipitated calcium oxalate. The precipitate is extracted
twice with 250 c.c. of water and concentrated (to about 250 c.c,)
until crystals appear on the surface.
Tyrosilie.—On cooling, a brown, crystalline crust of impure
tyrosine separates. It is filtered, dissolved in the least quantity
of boiling water, boiled with a little animal charcoal, and
filtered. On cooling, long, white, silky needles of tyrosine arc
deposited. Yield about 2 grams.
Reactions.—Warm a small quantity of the substance with a
drop of strong nitric acid and add ammonia. A yellow solution
is produced in the first case, which changes to deep orange with
ammonia (xanthoproteic reaction). Warm with a solution o^
mercury in strong nitric acid (Millon's reagent). The liquid
turns red, and a red precipitate is tlien formed.
Leucine.—The filtrate from the tyrosine is further con-
ccntrcitecl on the w^tqr-bath to a small bulk, when on cooling a
134               PRACTICAL ORGANIC CHEMISTRY

quantity (about 20 grams) of crude leucine in the form of a brown
crystalline crust separates, and is collected on a filter and
dried on a porous plate. It is converted into the ester
hydrochloricle as follows: the dry material is dissolved in
120 c.c. absolute alcohol and saturated with hydrogen chloride
(p. 93). The alcohol is removed- by distilling under reduced
pressure at a temperature not exceeding 40° in the apparatus
shown in Fig. 66 (p. 94). The same quantity of alcohol is added,
saturated with hydrogen chloride, and removed as before. The
residue, which consists of the ester hydrochloride of leucine and
small quantities of other amino-acids, is converted into the free
ester in the following way : it is dissolved in about one-quarter
its volume of water, to which an equal volume of purified ether
is then added. The liquid is well cooled in a freezing mixture
and a cooled 33 per cent, solution of caustic soda is slowly added
until the liquid is just alkaline, and then an equal volume of a
saturated solution of potassium carbonate. The mass is now
well shaken and the ether decanted. In this way the ester,
which is rapidly hydrolysed by alkali at the ordinary tempera-
ture, is liberated from the hydrochloride without decomposition
and dissolves in the ether. The residue is kept in the freezing
mixture, a fresh quantity of ether, more caustic soda solution, and
sufficient solid potassium carbonate to form a pasty mass are
added in succession, shaken up thoroughly and the ether de-
canted. The residue is extracted two or three times with fresh
ether and the united extract, freed as far as possible from water,
is shaken up for a minute with solid potassium carbonate and
then dehydrated overnight with anhydrous sodium sulphate.
The ether is removed on the water-bath and the residue distilled
at a pressure not exceeding 15 mm. The colourless liquid, which
distils at 80—100°, has an ammoniacal smell and is nearly pure
leucine ester. Yield 10—15 grams. The ester is readily
hydrolysed by boiling five times its weight of water with reflux
condenser until the alkaline reaction disappears (about an
hour). The liquid is then concentrated on the water-bath until
crystals separate on the surface and cooled. The leucine
may be recrystallised from dilute alcohol or dissolved in
the smallest quantity of hot water and alcohol added until
a turbidity appears. It forms small glistening plates, which
melt and sublime at 170°. See Appendix, p. 270,
GRAPH StKlAR

Grape Sugar.   (Glucose, Dextrose.)
Soxhlet, J.prakt. C/i., 1880, (2) 21, 245.
CIloOH.CHOM.CIIOH.CHOH.CHOH.CO.H
250 grms. cane sugar.
750 c.c. spirit.
30 c.c. cone, hydrochloric acid.
The spirit and acid are mixed and warmed to 45—50°, whilst
the iincly*po\vclercd cane-sugar is gradually added and stirred.
When the sugar has dissolved the solution is cooled, and a few
crystals of anhydrous grape-sugar added. On standing for a
day or two the grape-sugar deposits in the form of fine crystals,
which continue to increase in quantity. When no further de-
position is observed, the crystals arc filtered and washed with
spirit. The sugar may be purified by dissolving in a little
water to a syrup, and adding hot methyl alcohol until a turbidity
appears. On cooling, the grape-sugar crystallises out.
Cum; sugar.                       (llucosc.           I'Yuctuse.
Properties.—Colourless crystals ; m. p. 146° ; soluble in hot
and cold water, insoluble in alcohol.
AVmvVVw.v.•—i. Add to a little of the solution of glucose a few
drops of caustic soda, and warm. The colour changes from
yellow to brown.
2. Add to 2 or 3 c.c. of the solution two or three drops of copper
sulphate, and then caustic soda, until a clear blue solution is
obtained, and heat to boiling.    Red cuprous oxide is precipi-
tated.
3.   Add a few drops of glucose solution to half a test-tube
of ammonio-silvcr nitrate solution  and place the test-tube in
hot water.    A mirror of metallic silver is formed.
4.   Dissolve about 0*5 grain of glucose in 5 c.c. of water, and
add a solution of phenylhydrazine acetate, made by dissolving
i gram of phenylhydnizine in the same weight ofjjlacial acetic
acid, and diluting to 5 e,c,    Mix live solatia^ and warm in the,
136                PRACTICAL ORGANIC CHEMISTRY
_____________________________________________________^
water-bath.    In a few minutes the yellow crystalline phenyl"
glucosazone (in. p. 204—205°) is deposited.
5. Mix a few drops of a glucose solution with a few drops o^
an alcoholic solution of a-naphthol and pour slowly down the sid^
of the test-tube a few drops of cone, sulphuric acid. A violet
colouration is produced. (Molisch's reaction.) See Appendix*)
p. 271.
Benzene.
Pure Commercial Benzene, obtained from coal-tai"
naphtha, should distil within one degree (80—Sic), and solidify
completely when cooled to o°. Other tests are as follows *
shaken with concentrated sulphuric acid for a few minutes, the
acid should not darken, and a drop of bromine wafer should
not be immediately decolourised. A single distillation over a
few small pieces of sodium, which absorb any traces of water, is
usually a sufficient purification. If the benzene impart a brown
or black colour to the sulphuric acid, it must be repeatedly
shaken with about 20 per cent, of the acid until the latter
becomes only slightly yellow on standing. This is done in a
stoppered separating funnel, and after shaking fora few minutes
the mixture is allowed to settle, and the lower layer of acid
drawn off. The benzene is then shaken two or three times with
water to free it from acid, carefully separated from the aqueous
layer,, and left in contact with fused calcium chloride until the
liquid becomes clear. It is then decanted, frozen in ice, and
any liquid (carbon bisulphide, paraffins) carefully drained off,
and the benzene finally distilled over sodium.
Properties.—Mobile, colourless liquid ; m. p. 5*4° ; b. p. §P'4C ;
sp. gr. 0*874 at 2°°' Coal-tar benzene usually contains a little
thiophene, C4H4S, which may be detected by dissolving a fe\v
crystals of isatin (see p. 229) in concentrated sulphuric acid and
shaking up with the" benzene. If thiophene is present, a blue
colour is produced (indophenin reaction).
Fractional Distillation.—It is often possible to separate
almost completely by a single distillation, two liquids occurring"
together in a mixture when their boiling points lie widely apart.. _
The more  volatile  liquid first passes  over,  the temperature
suddenly rises, and the higher boiling liquid distils.
It is otherwise when a liquid consists of a mixture of sub-
Stances boiling at lifnperatures not very far removed from one
KKN/KNK

137

another, especially in the case of homologous compounds, such
as occur in petroleum and coal-tar naphtha. One distillation
suffices only to produce very partial separation of the different
substances, a portion of the less volatile liquid being carried
over in the first distillate, together $iih the more volatile body,

I

i!



D

Fi<!. 7^"» represents n seri<%s of simple and e.l'fi :iftit fnu'tinnntii)^ colunin1; or still-
heads. A is th.-it uf Vii^reux, in \vli <:h he coii-.trii'tidii1, :ir<- lonued by in-
ileiitin^ llu- tube it-.t-If; i-. is I Jnnpel's :olu nn und cmi-.i-.ts ol" a Imii.' wide tttbc
ille<i with tj;|;i-,s heads ; <•, M, and K ar<; cult nue, d.-vi-.rd by N'.MIIIV. and Tl mm-.,
1 e last brim', usci'ul wiicn lai-,j;<- ijitanii ies >f liijuid have to be di-,iillrd. con-
;ins a series ..f ^jass clisrs fused ,,n car.xl, which ran be removed IV, n the
i !>e ; D has a series of" pear-shaped I ulhs blown on the Mem, and K is; wide
i be with a series of constriciions in ea :h of \vhi<:h a small bent i',lass <lr ppin.i;
i In: is suspended in a i',an/e cup.
the temperature gradually rising tliroughont the distillation. In
only*' to effect separation of the several substances, recourse i1
had to the method of fractional distillation.
Tf|e liquid is distilled in a round  flask  over wire-gauze or.
better, in a fusible metal bath, a bit of ^rous pot or a coil <»i
I38              PRACTICAL ORGANIC CHEMISTRY
platinum-wire being placed in the flask to prevent bumping"*
The flask is surmounted with a fractionating column, in \vhicli
the thermometer is fixed. Various forms of fractionating columns
are used (see Fig, 76).
The effect of the columi%may be explained as follows: the
vapour given off from a mixture of liquids contains a larger pro-
portion of the more volatile constituent than the liquid. If this
vapour is condensed in its ascent, the vapour above this con-
densed liquid will be still richer in the more volatile constituent.
If, by a series of constrictions or diaphragms, the condensed
liquid is obstructed in its return flow, a momentary equilibrium
between liquid and vapour is established at each diaphragm, ancl
the longer the column the greater will be the amount of more
volatile constituent in the last portion of vapour to undergo con-
densation. This passes off by the condenser and is collected
in the receiver. The apparatus (Fig. 76, E) can be made out
of a piece of wide tubing. This is constricted in the blow-pipe
flame, near one end, and a piece of copper wire-gauze with a.
circular hole, carrying the little bent tube, is placed on the con-
striction. A second constriction is made and another gauze
diaphragm introduced. The number of diaphragms may vary
from 10 to 20, according to the degree of separation required.1
Commercial 50 per cent, and 90 per cent. Benzene
are mixtures of benzene and larger or smaller quantities of its
higher boiling homologues, viz., toluene (b. p, 110°) and the
xylenes (b. p. 137—143°). The constituents may be separatedtby
fractional distillation.
Fit up an apparatus with fractionating column and distil
200 c.c. 50 per cent or 90 per cent, benzene, at a regular spfed,
so that the drops falling from the end 'of the condenser may be
readily counted. Collect the distillate between every five degrees
in separate flasks. Redistil each of these fractions in order,
adding the next to the residue of the previous one in the
distilling-flask. Collect portions boiling below 85° and above
105°, between every two or three degrees. It will be found that
by a repetition of the process the liquid is gradually separated
into two large fractions, consisting chiefly of benzene and toluene,
and a number of smaller intermediate fractions. The following"
table gives the nolume in c.c., and the- boiling points
0C'* l899) 76, 700,
FRACTIONAL DISTILLATION

fractions obtained by this method from 200 c.c., 50 per cent,
benzene, each table denoting a complete series of fractionations,
using a simple column with two bulbs.

A,,
	a
 fi5-Qo'
	»?•-
	r>,
 05-100°
	j GO- 105"
	F.
 105-110"
	o.
 110-115"
	Resic

19 c.c.
	s;? <••<-•
	
	15 c.c.
	13 c.c.
	17 c.c.
	21  C.C.
	33 c


	A'
	r,',,
	cv.
	I )'.
	K'.
	F',,

k
	7"'-
	— —
	__
	85-105"
	105-108"
	io8-r]

ded
	
	
	(rnr c.H)
	
	
	

.l«-d
	
	
	
	
	
	


	
	
	(9 c.c.*)
	
	
	

dcd
	
	
	
	
	
	

i«:
	
	
	
	f,n r.r.
	
	

ded
	
	
	
	
	
	

K.
 d.-d
	
	
	
	
	(n c.c.")
	on  f

•frru--att-il
	
	
	7 r c
	
	
	


	
	
	
	
	(1 C.C.
	5 c.


	
	
	
	
	
	


	.S <".<:.
	.<;., «:.«.
	7 c.c.
	50 r.c.
	6 c.c.
	57 c.

Residue.

42 c.c.

.
''' 1

The fraction 79—81   is further purified in the manner already
described.
14°

PRACTICAL ORGANIC CHEMISTRY

PREPARATION 46.
Bromobenzeiie (Phenyl bromide), CcH6Br.
Cohen and Dakin, Trans. Chem. Soc., 1899, 76, 894; Cross
and Cohen, Proc. Chem. Soc., 1908.
50 grms. benzene.
120     „      (40 c.c.) bromine,
o* 5  „       pyridine.
The apparatus is similar to that shown in Fig. 63, p. 89, but tine
flask should be placed in a water-bath, in which it can be heated.,
and the tap-funnel may be dispensed with. The benzene, bro-
mine, and pyridine are placed in the flask and heated to 25—30°,
when a vigorous and steady evolution of hydrogen bromide
takes place, the gas being absorbed by the water in the beaker.
When the action slackens (about i hour) the temperature of tlie
water-bath is gradually raised to 65—70°, and the process
stopped when most of the bromine has disappeared and trie
evolution of hydrogen bromide has nearly ceased. The con-
tents of the flask are cooled and poured into dilute caustic soda,
solution contained in a separating funnel and shaken. Suffi-
cient alkali must be present to give an alkaline reaction after
shaking. The lower layer is drawn off and dehydrated over
calcium chloride. When perfectly clear the bromobenzene is
filtered or decanted into a distilling flask (200 c.c.) provided
with a thermometer and distilled over wire-gauze. Unchanged
benzene first passes over ; the temperature then rises rapidly
and the portion boiling at 140—170° is collected separately. It
is redistilled and collected at 150—160°. Yield 60 grams.
C0HC -1- Br2 = C0H5Br + HBr.
The pyridine acts as "halogen carrier," probably by forming"
the additive compound C5H5NBr2, which gives up its bromine to
the benzene.
Properties.—Colourless liquid ; b. p. 154—155° ; sp. gr. i"49<5
at 16°.
Hydrobromic Acid.—The weak solution of hydrobrom i c
acid which collects in the beaker in the course of the above re-
ETHYL BENZENE

14*

action may be concentrated by fractional distillation, as in the
case of hydriodic acid (p. 113), and used in the preparation of
bromotoluene (p. 167).    It boils at 126° at the normal pressure/
has a sp.gr. of 1-49, and contains about 47 per cent, of HBr!
See Appendix•, p. 271.

PREPARATION 47.

Ethyl Benzene, CGH5.C,H5

Fittig, Annalen, 1864, 131, 303.
60 grms. bromobenzene.
52     „      ethyl bromide (see p. 54).
26'5 „      sodium.

A quantity of ether, which has been freed from alcohol by
distilling over caustic potash, and dried over calcium chloride
and sodium (see p. 61), is poured into a round flask (i litre).
The amount of ether should be about twice the volume of the
mixed phenyl and ethyl bromides. The sodium, cut into thin
slices with the sodium knife, or squeezed into fine wire, is added
to the ether, and when all evolution of hydrogen has ceased,
the flask is attached to an upright condenser and immersed in
a vessel of ice-water. The mixture of bromobenzene and ethyl
bromide, both carefully dehydrated, is poured into the flask.
The reaction is allowed to commence spontaneously, the fact
being indicated by the appearance of the sodium, which be-
comes darker in colour and sinks to the bottom of the vessel.
Although the flask is allowed to remain in the outer vessel, and
is cooled by water and ice, the heat evolved often causes the
ether to boil. The flask is therefore not removed until the re-
action is over. It is convenient to leave it over night. The
liquid is then decanted from the sodium bromide, which has a
blue colour, into a distilling flask, and rinsed out once or twice
with ether, The ether is removed on the water-bath, a bit of
porous pot being added, and the residue is fractionated with a
fractionating column. The portion boiling at 132—135° is
collected separately. Yield 20—25 grams.

CcH6Br + C2H6Br + 2Na = C0H6.C2H6 + 2NaBr.

Properties.—Colourless liquid; b. p. 134°
22'5°.    See Appendix, p. 273,

sp. gr. 0-8664 at
PRACTICAL ORGANIC CHEMISTRY

PREPARATION 48.
Nitrobenzene, C(iH5NO2
Mitscherlich, Annalen, 1834, 12, 305.
50 grms. benzene.
So     „      (60 c.c.) cone, nitric acid, sp. gr. 1*4-
120     „      (60 c.c.) cone, sulphuric acid.
The two acids are mixed and well cooled, and then slowly
added from a tap-funnel to the benzene, which is contained in. • <•
flask (-i- litre). The contents of the flask are well shake ft a.ltcT
each fresh addition. Nitrous fumes are evolved, and a consider-
able amount of heat developed. Care must, however, be taken
that-the temperature does not exceed 50—60° by immersing' tlit*
flask, if necessary, in cold water. The nitrobenzene sepa.rii.tt-s
out as a brouli, oily layer on the surface of the acid licjUH*.
When the acid has all been added, an operation which. l:ii*t^
about half an hour, the mixture is heated for about twenty
minutes on the water-bath, and again well shaken. The con-
tents of the flask, on cooling, are poured into a stoppered sep;i-
rating-funnel, the lower layer of acid removed, and the nitro-
benzene washed free from acid by shaking once with w«ttt*t"
(50 c.c.), then with dilute carbonate of soda solution, and aysiin
with water, the oil being each time withdrawn from the bottom
of the vessel. The nitrobenzene, separated as carefully as pos-
sible from water, is allowed to stand over a few pieces of fused
calcium chloride, and shaken occasionally until the liquid i'.-»
clear. The yellow liquid is decanted, or filtered from tii«^
calcium chloride, and distilled in a distilling-flask, with con-
denser tube only. At first a little benzene passes over ; tlitr
temperature then rises, and the nitrobenzene distils at 204
20f, and is separately collected. The brown residue consist^
of dinitrobenzene, the quantity depending upon whether tilt-
temperature during nitration has been allowed to rise too liiylx.
Yield about 60 grams.
__           CGHG 4- HO.NO3 = C0H5NOo + H2O.
The function of the sulphuric acid is that of a dehydrating*
agent-taking up the water formed in'the reaction.
Properties.—Light   yellow   liquid,   with a   smell   of   bitter
AZOXYBKNZENK

almonds; 1>. p. 206 — 207°, sp. gr.  I'2o8 at  15°; m. p. 3*;
soluble in water, soluble in alcohol, ether, and benzene.

A'cui'/to//. — Pour a drop of nitrobenzene into a test-tub^ with

1  c.c. water and i c.c. glacial acetic acid.    Adda little zinc-dust
on the point of a penknife, and warm for  a  minute.    Dilute
with a few c.c. of water,   and add caustic soda solution until
alkaline, and pour a few drops into a test-tube half filled with
sodium  hypochlorite   solution.     A   violet  colouration,   which
gradually  fades,   is  produced, due to the presence of aniline
(see p. 150).    See Appendix^ p. 274.

P REPARATION    49.

Azoxybenzene,  CWN -- N .C(JHfj
\0/

Klingcr, /?<v., 1882, 15, 865.

200 grins, methyl alcohol
20     ,,     sodium.
30     ,,     nitrobenzene.

Attach an upright condenser to a round flask (J, litre).    Pour
in  the methyl alcohol and  add   the sodium  in   small   pieces,

2 — 3 grams at a time.    A good stream of water should pass
through the condenser,  but  otherwise  the   flask need not be
cooled.    When the sodium has dissolved, the nitrobenzene is
introduced, and the mixture boiled on a water-bath three   to
four hours.    The methyl  alcohol  is   then   distilled   off in   the
water-bath.    As  the   liquid   is   liable  to  bump,   owing   to the
separation of solid  mailer, it  is advisable to add a few bits of
pot.    When no more alcohol distils, the residue is poured into a
beaker of water and rinsed out. A. dark-coloured oil is deposited,
which soon solidifies, and is then washed by decantation, and
pressed on a porous plate.     Yield about 23 grains.     It is re-
crystallised, when dry, from ligrom, in which it is rather soluble.

•1-311,0.
crtics*— Yellow   needles ;    in. p.   36 .    vSee   Appendix*
PRACTICAL ORGANIC CHEMISTRY

Azoxybenzene from Nitrobenzene by Electro-
lysis.—Nitrobenzene can be conveniently converted intoazoxy-
benzene by electrolytic reduction. The apparatus required is
shown in Fig. 77.

It consists of a porous cell which forms the cathode chamber
and contains 20 grains nitrobenzene and 160 grams 2*5 per
cent, caustic soda solution. The two are kept well mixed
throughout the operation by a rapidly revolving stirrer. The
cathode is a cylinder of nickel gauze (12 cms. x 8*5 cms. = 100 sq.
cms.). The anode chamber is the outer glass vessel or beaker,

FIG. 77.
which contains a solution of sodium sulphate acidified with
sulphuric acid ; a cylinder of sheet lead serves as the anode.
An ordinary ammeter (A) and resistance (7?) are connected in
series with the battery and electrodes, and it is also useful,
though not essential, to insert a voltameter (F) between the
two electrodes. A current density of i to 5 amperes per 100 sq.
cms. is used and 15—20 ampere hours will complete the
reduction.1
The oily liquid which separates in the cathode chamber, and
1 The current may be obtained from a number of secondary batteries or from a
direct electric light circuit with a suitable resistance.                                  '•
AZOBENZENE

consists of azoxybenzene mixed with aniline and a little un-
changed nitrobenzene, is distilled in steam, which removes the
impurities. The residue then solidifies on cooling, and is filtered,
dried, and recrystallised. Yield 1 1 grams (60—70 per cent, of
the theory) (Elbs, Electrolytic Preparations, trans, by R. S.
Mutton, p. 76).

PREPARATION 50.

Azobeiizene, CGH5N:N.CcHf,

Mitscherlich, Annalcn^ 1834,   12, 311.

5 grms. azoxybenzene.
15      „      iron filings.

The azoxybenzene and iron filings, both of which must be
carefully dried on the water-bath, are powdered together and
distilled from a small retort, which is conveniently made by
blowing a large bulb on the end of a piece of rather wide
tubing i-i~ cm. inside diameter, and then allowing the bulb
whilst hot to bend over. The mixture is carefully heated, the
burner being moved about until the contents are thoroughly
hot, and then the mixture is more strongly heated until nothing-
further distils. The distillate, which forms a solid, dark- red
mass, is washed with a little dilute hydrochloric acid and water,
and then pressed on a porous plate. It is crystallised from
ligroin, in which it is very soluble.

QH.N  — N.C0H6 + Fe = CGH;,N : N.C0HS + FeO.

f;

Properties. — Red plates; m. p. 6SJ; b. p. 295°. See Appendix ^
P- 274-
Azobenzene from Nitrobenzene by Electrolysis.— A
good, yield of azobenzene can be obtained by the electrolytic
reduction of nitrobenzene in alcoholic solution. The apparatus
is similar to that shown in Fig. 77, p. 144, but in the present
case the cathode chamber is the outer vessel, which should be a
deep, narrow glass cylinder or beaker. The cathode liquid is
a solution of 20 grams nitrobenzene and 5 grams sodium acetate
crystals in 200 c.c. 70 per cent, spirit. The cathode is a cylinder
of nickel gauze. A large porous cell forms the anode chamber,
COHEN'S ADV. P. o. c.                                             L
PRACTICAL ORGANIC CHEMISTRY

and contains a cold saturated solution of sodium carbonate.
The anode is a wide strip of sheet lead. A current density of
6 to 9 amperes per 100 sq. cms. is passed for 17*4 ampere hours,
and then a lower current density for a further i—2 ampere hours.
During the reduction the cathode liquid becomes very hot and
the alcohol which evaporates must be replaced. The cathode
liquid at the end of the process contains, in addition to azoben-
zene, azoxybenzene and hydrazobenzene. It'is poured into a
flask and the hydrazobenzene is oxidised to azobenzene by
aspirating a current of air through the solution for half an
hour. The greater part of the azobenzene separates and can be
filtered ; the remainder, which is less pure, is precipitated from
the filtrate by the addition of water. It is recrystallised from
ligroin. Yield 90 per cent, of the theory.
(Elbs, Electrolytic Preparations, trans, by R. S. Hutton,
p. 78.)
PREPARATION 51.
Hydrazobenzene (Diphenylhydrazine)C6H5N H. N H QH6
Alexejew, Zdtschr.f. Chein.,  1867, 33; 1868,497; E.Fischer,
Anleitung sur Darstdlung org. Praparate, p. 23.
50 grrns   (42 c.c.) nitrobenzene.
54     „     caustic soda (in 200 c.c. water).
50 c.c. alcohol.
100—125 grms. zinc dust.
The apparatus is shown in Fig. 78. It consists of a1 large,
round, wide-necked flask (i-| litre) furnished with a cork perfor-
ated with three holes. Through one hole a stirrer, moved by a
water-turbine or electric motor, passes in the manner shown in
Fig. 78. To the stem of the stirrer a short, wide glass tube is
attached which revolves in the annular space formed at the end
of an adapter by fusing to it an outer concentric piece of wider
tubing. When this space is filled with water it serves as a
water seal. Through a second hole a wide glass tube is inserted
by which the zinc dust is introduced, and is fitted with
a cork. The third hole is furnished with an adapter to which
a condenser is attached. The nitrobenzene, caustic soda solu-
tion, and the alcohol are poured into the flask and the stirrer set
MVI)KA/X)HKNXKNK

147-

in rapid motion so that the contents are kept thoroughly agitated
The thorough mixing of the materials is essential to the success

of the process.    The zinc dust is added  in quantities of 3__4

grains at a time through the wide glass tube, which is closed by
a cork after each addition. The mixture soon becomes warm
and eventually boils. To prevent the liquid boiling over the
frothing is allowed to subside before fresh zinc dust is added.
The operation is usually completed in J hour, when the liquid,
which has first a deep
red colour (a/.obcnzene),
becomes pale yellow. To
examine the colour a
sample should be with-
drawn with a pipette
and filtered. The stir-
ring is continued for
another ..]. hour. A litre
of cold water is added
which precipitates the
hyclrazobcnzene. The
mixture of hydrazoben-
zene and zinc residues
is filtered at the pump
and washed free from
alkali with water. The

precipitate is then pressed clown and extracted with 750 c.c.
of spirit on the water-bath with reflux condenser and filtered.
On cooling in a freezing mixture, the hydni/.obcnzcne crystal-
lises in colourless plates, which are filtered and washed with a
little spirit. The mother liquor is used for a second extraction
of the zinc residues, and from the filtrate a further quantity
of hyclra/obenzene is precipitated with water. If the second
crop of crystals have a yellow colour crystallisation from alcohol
will remove it. Yield 30 35 grams.

•\ 3/,n  I GNuOIl ™ C,jII,,NII.NnCr,IJn -I- 3/11(011),,

.s\ —Colourless plates ; in. p. 125".
Kt'ih'titins.— i.   Heat   a  small  quantity  in  a  dry test-tube.
Notice the colour.   On cooling add a little writer and pour a few
drops into a bolutiou of sodium hypochloritc.    A violet

L  2

148

PRACTICAL ORGANIC CHEMISTRY

tion indicates aniline.    2CBH3NH.NH.CCH5 = C0H6N:NC0H5=
2CGHi,NK,
2. Heat a small quantity with Fehling's solution and observe
the formation of cuprous oxide. The hydrazobenzene is oxidised
to azobenzene.
Benzidine.—Five grams of powdered hydrazobenzene are
shaken with 125 c.c. hydrochloric acid (3 per cent.) at 20—30°. In
a quarter to half an hour the substance will have completely dis-
solved. Finally, the mixture is heated to 45—50°, a little water
added to redissolve any benzidine hydrochloride, and filtered
warm. The benzidine is precipitated from the solution of the
hydrochloride by adding to the cold solution an excess of caustic
soda solution. It is filtered and washed free from alkali, and •
recrystallised from boiling water or dilute alcohol. It crystallises
in plates with nacreous lustre, m. p. 127°.
C6H5NH.NHCGH5 - NH2C0H4.C0H4NH3.
See Appendix, p. 275.
PREPARATION 52.
Phenylhydroxylamine, C0H5.NH.OH
Bamberger, Ber., 1894, 27,  1548; Wohl, Ber., 1894, 27, 1432 ;
Friedlander,  Theerfarbenfabrikation, IV.. 48.
6 grins, ammonium chloride (in 200 c.c. water).
12     „      nitrobenzene.
18     ,,      zinc dust.
Mix the nitrobenzene and ammonium chloride solution in a.
flask (i- litre). The zinc dust is added in portions of about a gram
at a time with constant shaking or stirring by turbine, the tem-
perature being maintained below 15°, by cooling if necessary in ice
water. The addition of the zinc dust should take about an hour.
The shaking is continued for another quarter of an hour, when
the smell of nitrobenzene will have disappeared. The contents
of the flask are filtered and washed with 100 c.c. water, so that
the water trickles slowly through the filter. The filtrate is
saturated with clean salt (80 grams) and cooled to o°. Colour-
less crystals of phenylhydroxylamine fill the liquid. They are
filtered at the pump, dried on a porous plate, and recrystallised
if necessary from benzene. Yield C—8 grams.
ANILINE                                    149

Properties*—Colourless needles ; in. p. Si '.

/UW/Y/VV/.V.—Add to a solution of phenylhydroxylamine Feh-
linjj's solution and warm. Cuprous oxide is precipitated. To
another portion add amtnoniaca! silver nitrate and warm. Silver
is deposited. See Appendix, p. 276.

Nitrosobenzene...........Dissolve 4 grains of phenylhydroxyl-
amine in the equivalent quantity of ice cold 6 per cent, sulphuric
acid (4 c.c. in 66 c.c. water), and add a well-cooled solution of 4
grams potassium bichromate in 200 c.c. water. Yellow crystals <»f
nitrosobenzene are deposited which distil in the vapour of steam
with an emerald-green colour ; m. p. 67-68''.

C,,Hfi.NHOH + O = C,,H;,NO 4- H,O.

p-Aminophenol.--AcUl gradually i ^ram of phenylhydroxyl-
amine to ro c.c. cone, sulphuric acid and 15 grains of ice, dilute
with 100 c.c. of water and boil. Test a small, sample with bi-
chromate solution in order to see if the smell is that of nitro
bcnxene or quinone. In the latter case conversion is complete.1.
The acid liquid is neutralised with sodium bicarbonate, saturated
with common salt and extracted with ether. On distilling off
the ether, w-amidophcnol crystallises ; m. p. 186".

C,,Iifl.NH.OH •= OIi.C(.II.,.NH,.

PREPARATION  53.
Aniline (Aminobcn/ene ; l*henylamine\ C(;H;,NI1,>
Xinin, AnnafeH, 1842, 44, 2tSj.
50 ^rms. nitrobenzene.
90    „    granulated tin.
170 c,c. cone, hydrochloric add (sp. j^r, ri6'i.
Introduce the tin and nitrobcnxeno into a round flask n.l
litre), and fit it with a straight upright, tube about 2 leet lon^
(air-condenser). Meat the mixture for a few minutes on the
water-bath. Then remove the flask and add the concentrated
hydrochloric acid in quantities of 5 ro c.c. at a time, and shake
repeatedly. The liquid should become hot and boil quietly ;
but, if the action becomes too violent it must be moderated by
150               PRACTICAL ORGANIC CHEMISTRY

cooling the flask in cold water. In the course of A- — f hour all
the acid should have been added ; the flask is then replaced on
the water-bath without the air-condenser, and heated for an
hour or more until the reduction is 'complete. This is ascer-
tained by the absence of any smell of . nitrobenzene. The
contents of the flask, on cooling, solidify to a crystalline mass
(a double salt of stannic chloride and aniline hydrochloride)
Whilst still warm, water (100 c.c.) and strong- caustic soda.
solution (140 grams in 200 c.c. water) are added until the
stannic oxide, which is first precipitated, nearly redissolves
and the liquid has a stongly alkaline reaction. If the mixture
begins to boil during the addition of the caustic soda solution
it must be cooled. The aniline, which separates out as a darlc-
coloured oil, is distilled in steam. The apparatus is shown in
Fig. 68, p. 107. The flask containing the aniline is gently
heated on the sand-bath, and steam is passed in from the tin
bottle. It is advisable to heat the aniline mixture on the
water-bath before steam is admitted, as otherwise a largfe
quantity of water condenses in the flask. On distillation,
aniline and water collect in the receiver, the former as a colour-
less oil. When the distillate, as it comes over, appears clea.r
instead of milky, the distillation is stopped. The oil is no^v
extracted from the distillate by shaking up the liquid in n
separating-funnel three times with small quantities (30 c.c.) ox
chloroform. The chloroform solution, separated as far as possible
from water, is further dehydrated by adding a little solid potas-
sium carbonate. The clear liquid is decanted into a distilling- -
flask, the flask rinsed with a little=**%hloroform, and the
chloroform removed by distillation until the temperature
reaches 100°, when the receiver is changed. Aniline distils rtt
182 — iS3°,andhas usually a faint amber colour. Yield, abou.1
30 grains.

2C0HaN02 + sSn -h I2HC1 = 2C0H5NH2 + 3.SnCl4 + 4H2O
Properties. — Colourless, highly refractive liquid, which soon
darkens in colour ; b. p. 183° ; sp. gr. 1*0265 at I5°-
\                            Reactions. — T. Add a drop of the oil to a solution of bleacli-
ing powder or sodium hypochlorite. An intense violet colour n.-
f                         tion is produced, which gradually fades.
**    |J                     2. Heat a drop of the oil with a few drops of chloroform, and
ACKTANILIDK                                 I5l

about i c.i'. of alcoholic potash, hi the fiuue-iiipboanL Phenyl
carbamine is formed, which possesses an intolerable smell.
(Hofmunn's reaction for primary amines.)

3.  Add to a drop of aniline in a basin a few drops of con-
centrated sulphuric, acid, and stir with a glass rod.    Then add
a few drops of potassium bichromate solution.      An  intense
blue colour is obtained.

4.   Dissolve a few drops of aniline in 5 c,c. dilute hydrochloric
acid, cool under the tap and add a few drops of a solution of
sodium nitrite.    Then pour some of the solution   into   about
half a gram of phenol dissolved in a few c.c. of caustic soda
solution.    An orange solution of sodium hydroxya/obenxene is
formed (see Reaction 6, p. 163).

Qjn;.NH.,MCH-IINO,-C<iII;-.N,CH-2ll.)0
C,,IliVN/:i + C1iHfl.ONa--Cu[Ir,.N2CJiri.,C)Njr

+ NaOH                            4-NaU-r-IUJ.

See Appendix, p. 277.

PR KPA RATION   54.
Acetanilide (Phenylacetamide), C,,Hr(.NH.C( ).CH;,
(i. Williams, Trans. Chcm, *SV-»r., 1864, 2, 106.
. 25 grms. aniline (freshly distilled).
' 30   c.c.   glacial acetic acid.
Boil the mixture gently in a flask (250 c.c.), fitted with an air-
condenser, for a day (7 <S hours). As the liquid solidifies on
cooling, it is at once poured out, while hot, into a basin of cold
water (500 c.c.). It is filtered and washed with cold water.
Acetanilide crystallises best from hot water, in which, however,
it is not very soluble. Place the moist acetanilide in a large
basin, and add gradually about a litre of boiling water. If the
substance does not dissolve completely on boiling, a small quan-
tity of spirit will bring it into solution. Kilter through a large
fluted filter or hot-water funnel (p. 53) and set the solution aside
to crystallise. If the product is dark coloured it is redissolved
PRACTICAL ORGANIC CHEMISTRY

as before, and heated with a little animal charcoal (5 — 10 grams)
for half hour and then filtered.    Yield, 30 — 35 grams.

Properties.— Rhombic plates ; m.p. 112° ; b.p. 295°.

Reaction. — Introduce about 0*5 gram of the substance into a
test-tube, and* add 3 c.c. concentrated hydrochloric acid. T3oil
for a minute. On diluting with water, a clear solution is ob-
tained.

See Appendix, p. 278.

PREPARATION   55.
p-Bromacetanilide, C0H4

\---                T

Remitters, Ber., 1874, 7, 346.

5  grms. acetanilide.

25 c.c. glacial acetic acid.

6 grms. bromine.                                       ^

Dissolve the acetanilide in the acetic acid in a flask (-| litre),
and add gradually the bromine, dissolved in about twice its
volume of glacial acetic acid, and shake well. When tlie
bromine has been added, let the mixture stand \ hour rind
then pour into 200 c.c. water and rinse out with water.
Filter the crystalline precipitate at the pump and wash three or
four times with water. Press it well down and let it clrnin.
Dissolve the moist substance in spirit (about 60 c.c.) ;mcl
pour into a beaker to crystallise. Filter the crystals, wjtsh
with a little dilute spirit, and dry on filter paper. Yield 6 — 7
grams.

C0H6NH.C2H3O + Br2 = C6H4Br.NH.C2H;5O4-HBr

Properties.-^Colourless needles; m.p. 165 — 166°. On liy-
drolysis with concentrated hydrochloric acid, /-bromaniline is
formed (see above reaction for acetanilide).
p-NJTKANlLINK

PKKI'ARATION   5(1.
p-Nitr aniline.
P>endcr and Erdmnnn, Chcwischc Priiparatcnfawde, vol. ii.
]). 438.
25 grms. ace t anil ide.
25 c.c. acetic acid (glacial).
50   „   cone, sulphuric acid.
10   „   fuming nitric acid (sp. gr, 1-5).
The acetanilide, acetic acid, and sulphuric acid arc mixed by
means of a mechanica.1 stirrer and cooled in a free/ing mixture.
The fuming nitric acid is then gradually added from a tap-
funnel at such a. speed that, the temperature does not exceed
20 . After the acid has been added, the mixture is stirred for
an hour and poured on to ice. The product is then diluted
with water, left to stand for a time, filtered, washed, and dried
on a porous plate. It maybe recrystallised from dilute alcohol,
but is usually pure enough for further treatment. Yield is
So per cent, of the theory ; the remaining 20 per cent, is ortho-
compound and "remains in solution ; m. p. 207°.
C(; H ,, N II . CO C II, + 1 1 N C), - N ( )., C(i 1 1 .,. N 1 1 . C O C I-T « + H,,O
' °i "
The /'-nitracetanilide is either boiled with 2\ times its weight of
concentrated hydrochloric acid, or heated on the water-bath
with twice its weight of equal volumes of sulphuric acid and
water until the liquid remains clear on diluting with water.
The /MI it ran 5 line which is now present in the liquid as the hydro-
chloride or sulphate, is diluted with water and precipitated by
the addition of an excess of caustic soda or ammonia. When
cold, the yellow crystalline precipitate is filtered, washed and
re-crystallised from boiling writer. Yield, 25 grams.
Ncx.c^iii.Nircocn, -i- 11,0 i no ^ N()O.C:(!II.,.NII,.IICI
1                                '  H rii,('O(.>n
Properties.— -Yellow needles; in. p. 147 ; soluble in hot
water ; very soluble in alcohol.
154               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 57.
m-Dinitrobenzene.   Q>H4M"

Deville,  Ann.   Chim.  Phys.,   1841   (3),  3,   187;   Hofmann,
Muspratt, AnnaJcn^ 1846, 57, 214.

30 grms. nitrobenzene.

35     „     (24 c.c.) fuming nitric acid ; sp. gr. 1*5.

35     „     (20 c.c.) cone, sulphuric acid.

The acids are mixed in a flask (500 c.c.), and the nitrobenzene
added in portions of 5 — 10 c.c. at a time. Heat is evolved, and
the mass becomes somewhat deeper in colour. When the nitro-
benzene has been added, the flask is heated for a short time on
the water-bath. A few drops are then poured into a test-tube of
water. The dinitrobenzene should, if the reaction is complete,
separate out as a hard pale yellow cake. If it is semi-
solid, the heating must be continued. The contents of the flask
are then. poured, whilst warm, into a large quantity of water.
The dinitrobenzene, which separates out, is filtered at the pump
and well washed with water. It is then dried. The yield is
nearly theoretical. A few grams should be recrystallisecl from
spirit. The remainder may be used for the next preparation
without further purification.

*        CCH3.NO2 + HNO3 = C0H4(NO2)2+H2O
Properties. — Colourless  long needles ; m. p. 90"' ; b. p. 297°,
See Appendix i p. 279.

PREPARATION   58.
m-Nitraniline.   CG

Hofmann, Muspratt, Annalen, 1846, 57, 217.
25 grms. 7;/-dinitrobenzene.
75     „     (95 c.c.) spirit.
12     „     (13 c.c.) cone, ammonia.
The powdered dinitrobenzene, spirit and ammonia, are mixed
together in a flask (-| litre) and weighed.    Hydrogen sulphide,
m-NITRANILINE

washed through water, is passed into the dark red pasty mass,
which is occasionally shaken.* The clinitrobenzene slowly
dissolves, whilst, at the same time, flakes of crystallised sulphur
are deposited. When the gas has been passing- for an hour the
flask is removed and heated on the water-bath fora few minutes.
After cooling, the liquid is again saturated with hydrogen
sulphide and then heated on the water-bath as before. When
the gas has been passing in a steady stream for fully two hours
the process is complete. Water is now added to the liquid until
nothing further is precipitated. The mixture is filtered at the
pump and washed with a little water. The solid residue is
transferred to a flask and shaken up with successive small
quantities of hot dilute hydrochloric acid and the liquid
decanted through the original filter. The nitraniline dissolves,
leaving the sulphur. When no more nitraniline is extracted
(this may be ascertained by adding ammonia in excess to
a portion of the acid solution, when no precipitate is formed),
the acid solution is somewhat concentrated, cooled, and con-
centrated ammonia added. The w-nitraniline is precipitated,
filtered when cold, and purified by recrystallisation from
boiling water. The filtrate from the nitraniline may be concen-
trated on the water-bath and a further small quantity obtained.
Yield, about 15 grams.

/ies.— -Yellow needles;   m. p. 114°;   b. p. 285°.    With
tin and hydrochloric acid it is reduced to w-phenylenediamine,

m-Phenylenediamine. Dissolve 30 grams stannous chloride
(SnClo + 2! !,,()) in 50 c.c. cone, hydrochloric acid in a round flask
(}> litre) and gradually add 5 grams ;;/-nitraniline. The mixture
is heated on the water-bath until no precipitate is formed, on
adding water (\ hour). The liquid is diluted with 500 c.c.
water, heated nearly to boiling and a current of hydrogen
sulphide passed in until all the tin is precipitated as sulphide
(A - 4 hour). With this object a small quantity should be
filtered and tested from time to time by passing in hydrogen
sulphide. The precipitate is left overnight to subside, the clear
liquid decanted and the residue filtered at the pump through a
156               PRACTICAL ORGANIC CHEMISTRY

double-filter. The clear filtrate is concentrated on the water-
bath until crystallisation commences and allowed to cool.
The crystals of the hydrochloride of phenylenecliamine sepai'ate
and are filtered, A further quantity may be obtained by con-
centrating the mother-liquors. Yield 6*5 grams,

Reaction. — Dissolve a few crystals in water, acidify with
dilute hydrochloric acid, and add a drop of sodium nitrite solu-
tion. A deep brown solution (Bismarck brown) is obtained.
See Appendix, p. 279,

;                                                           PREPARATION 59,
Dimethylaniline, C0HflN(CH3)3
Poirrier, Chappat,./a/jm&, 1866, p. 903,
20 grms. aniline hydrochloride,
15    „     aniline.
22   „     methyl alcohol.
The aniline hydrochloride is prepared by gradually ad.cling"
cone,   hydrochloric  acid to aniline  (20  grams  in a beaker)
until a drop brought on to a piece of filter paper, stained with
:                           methyl violet, turns it green.    The liquid is quickly cooled   and
stirred so as to produce small crystals.    It is then filtered, well
;                           pressed and dried on a porous plate.    The dry hydrochloride is
'       ,                     brought into a thick-walled tube closed at one  end, and   the
mixture of aniline and methyl alcohol added.    The tube is   then
;                           sealed  in the  ordinary way  and heated in the tube furnace
i                           gradually to 150° during two hours, and then to 180—200° for
j                           six hours  more.    The contents  of the  tube  divide  into    two
I                               layers, the lower one consisting of the  hydrochloride  of   the
J                           base and water, and the upper one of the free bases.   The whole
j                            of the contents are poured out into a large separating funnel,
;|                            and caustic soda added in excess.   The addition of a little ether
II                              causes the bases to separate out more readily.    The top layei*
f!    I                      is removed, and the lower aqueous portion is shaken up  twice:
p-NrrROSODIiMKTliYLANlLINK                     157

quantities  of ether.    The ethereal solution is de-

hy 1*.^ S&d    over solid caustic potash, the liquid filtered and the
*"    ~^iTi*>ved on ^1C wa-ter-bath.    The residue is now boiled
c:   £>'i"Lllls ace^c anhydride, using an upright condenser, for
-.     ~~   r in.   the same flask, the side limb of which is stoppered.
^i              ja^<^iits are then distilled.    Unchanged acetic anhydride

Pas -     -   o^r°r ilt 13O~I5°° ; the thermometer then rises, and the
l^c5ili"K al 1 90 -200 Ms collected separately.    When the
tc»n.iperature is reached, it is advisable to keep only the
^^^  °f^le ^o^clenscr filled with  water.    The  distillate
i"^K*^lt: am^er colour.    Yield, 20 grams.    The residue in
s^     consists  of acetanilide   and  methylacetanilicle  and
^  on cooling'.

.s liquid ; b. p. 192'- ; sp.gr 0*957 at 20°.
" — Warm, with an equal volume of methyl iodide ; the
quatcrnary ammonium iodide will be formed,

*                                                              PREPARATION 60.
i                                     p-Nitrosodimethylaniline,
,oNN-CH:;)-                    /N(CHa)2   I
;                               Qll/     ;o     or     C(ill,<
>                                      V                       XNO       4
i-,   Caro, /)<v.,  1874, 7, 810 and 963 ; Meldola,  Trans.
C/K?M.   ^'i><~., 1881, 39, 37-
120 grins, dimclhyla.nilinc.
53     „      (45 c.c.) cone, hydrochloric acid diluted with
Ioo c.c. of water.
I 3     „      sodium nitrite (in 20 c.c. of water.)
THc   cliiiicthylaniline is dissolved in the dilute hydrochloric
acid  ixa  SL  Ijcakcr and cooled in a freezing mixture.    The sodium
•

158                PRACTICAL ORGANIC CHEMISTRY
nitrite, dissolved in a small quantity of water, is then slowly
added with frequent stirring. The separation of the hyclro-
chloride of nitrosodimethylaniline in the form of small yellow
needles soon begins, and the liquid is gradually filled with, a
thick crystalline deposit. When, after standing for a short time
(half an hour), no further increase in the quantity of crystals is
observed, the mass is filtered at the pump and washed with
spirit, to which one or two c.c. of concentrated hydrochloric
acid has been added. It is then washed once or twice with
spirit, drained and pressed on a porous plate. Yield, nearly
theoretical. It may be recrystallised by adding small quantities
of hot water, until the salt is just dissolved, and then setting'
aside to cool. If the free base is to be prepared, recrystallisa-
tion is unnecessary. Ten grams of the hydrochloride are-mixed
into a paste with water in a flask, and caustic soda solution added
in the cold until alkaline. The yellow colour of the salt changes
to green of the free base. Sufficient ether is added to dissolve
the green precipitate. The ethereal solution is carefully
separated by means of a separating-funnel and most of the ethei'
is then removed by distillation. The remaining liquid is poured
out into a beaker and set aside to crystallise. The base remains
on evaporation of the ether in the form of brilliant green foliated
crystals.
CGH5N(CH3)2HC1+HNO2-(NO)C0H4N(CH3).,HC14-H1JO
Properties.—Large green foliated crystals ; m. p. 85".
Reactions.-—i. Dissolve a few crystals in dilute hydrochloric
acid and add a little zinc dust. The solution is decolourised
through the formation of dimethyl ^-phenylenediarnine,
(CH3)aN.C8H4NH2.
2.   Warm a few of the crystals with yellow ammonium sul pli i de
solution for a few minutes, acidify with hydrochloric acid,   and
finally add a little ferric chloride.     A deep blue colouration- is
produced, due to the formation of methylene blue.
3.   Dissolve 6 grams of caustic soda in 250 c.c. of wa'ter   mid
heat to boiling.     Add 5.grams of the hydrochloride of nitroso-
dimethylaniline gradually.    The free base, which separates out in
oily drops, is allowed to dissolve before each fresh addition*      The
boiling is continued until the dark green colour of the liquid
, i
\ I

THIOCARBANILIDE                     I

changes to reddish-yellow. Dimethylamine is evolved and is
easily recognised by its smell. After cooling, acidify the liquid
in the flask and extract with ether. On distilling off the ether,
nttrosophenot (quinoncoximc) remains in the form of dark-
coloured crystals, which are difficult to purify.

f"  VI   ./   ^(Cri"^   .   IT i   ,•}.....p   TY   ,/ O           i   XT T4 / r1 TJ   \
C(}   '>\NO         +    -   """    (5   >}\NOH+    H^H.V2
The presence of a nitroso-compound may he detected as
follows : Melt together a minute quantity of nitrosophcnol and a
few crystals of phenol. Add about 2 c.c. concentrated sulphuric
acid and warm very gently. A blue solution is obtained, which
changes to red on dilution with water, and back to blue on
adding alkali (Liebermann's "nitroso" reaction ; see Reaction,
p. i So). See Appendix, p. 280.
1'KKl'AKATJON 6l.
Thiocarbanilide(Diphenylthiourea), CS/^j 11S°S;'
\IN rK,ttns
Hofmann, Annalcn, 1849, 70, 14^,
30 grms. aniline.
30     „      carbon bisulphide*
30     „      absolute alcohol.
The aniline, carbon bisulphide,1 and alcohol are poured into a
round flask (\ litre), and heated for a day (8 hours) on the water-
bath with upright condenser. As hydrogen sulphide is evolved
the operation must either be conducted in the fume cupboard or
an exit tube must be attached to the top of the condenser tube
dipping into soda-lime. The contents of the flask solidify after
a time. When the. reaction is complete, the condenser is reversed,
and excess of carbon bisulphide and alcohol distilled off on the
water-bath. The residue is washed on to a filter with very dilute
hydrochloric: acid, to remove any unchanged aniline, and then
with water. The crystals are dried on a porous plate, and a por-
tion crystallised from spirit. Yield 30......35 grams.
2C0H{VN H., -i- CS,•:;. CS(N HC,.Mf,)2+ HaS
1 C;irbon bisulpliitU- 1>eing very volatile and <:xci;cdin;j;ly inflammable, great care
must be taken when usintf it in the neighbourhood of a ilame.
i6o

PRACTICAL ORGANIC CHEMISTRY

I

Properties.—Colourless rhombic plates ; m.p. 151°; scarcely
soluble in water, easily soluble in alcohol or ether.
Phenyl Thiocarbimide (Phenyl Mustard Oil), CGHSN:CS
The thiocarbanilide is boiled with two to three times tlie
weight of concentrated hydrochloric acid in a flask wit la <m
upright condenser for half an hour. It is decomposed into
triphenylguanidincj which remains as the hydrochloride in solu-
tion (it is subsequently separated) and phenyl mustard oil, wliich
separates out as a brown oil. On distilling the product in
steam, the phenyl mustard oil is carried over into the receiver.
It is separated by shaking out with ether, and removing" tlie
ethereal layer with a tap-funnel It is dehydrated over
calcium chloride, and decanted into a small distilling fla.sk.
The ether is removed on the water-bath and the mustard oil
distilled, with the thermometer, using a short condenser tul:>e»
Yield, 9—10 grams.
Properties.—Colourless oil with a peculiar smell; b. p. 220° ;
sp.gr. 1-135 at 15°.
Reactions.—i. Heat gently for a few minutes 0*5 c.c. phenyl
mustard oil, 0*5 c.c. alcohol and \\ c.c. concentrated ammonia-
On cooling, thiocarbanilamide, NH;j.CS.NH.CGH5, crystallises in
needles.
2.  Heat gently 0*5 c.c, phenyl mustard oil, and 0*5 c,c. aniline ;
on   cooling   and rubbing  with   a   glass   rod,   thiocarbanilide
crystallises.
3.  Heat on the water-bath in a small flask with upright con-
denser 3 grams of phenyl mustard oil and 10 c.c. absolute alcoliol
for 3  hours,  and  pour  into cold  water.    Phenylthiouretlioiio,
. C(jM5NH.CS.OC2H5,  separates out  and may be recrystallisccl
-from alcohol.    Yield, 2|- grams ; m. p. 67°.
4.  Heat a few drops of the mustard oil with yellow mercuric
oxide and notice the irritating smell of phenyl carbimicle.
CGH5N :CS + HgO = C0H5N :CO + HgS
Triphenylguanidina—In order to separate the tripheiiyl-
guanidine remaining in the flask as hydrochloride after distilling-
off the phenyl mustard oil, the hot solution must be somewhat
concentrated. The colourless salt, which crystallises out on. cool-
DIAZOBENZENE SULPHATE                    l6r

ing, is filtered and washed with a little water. It is then'warmed
gently for a few minutes with dilute caustic soda solution. The
base is liberated, filtered, washed with water and recrystalHsed
from spirit.

.NHCJi,,
20 S(N H CUH6)., + H Cl = CS N CuHfi -f C. N H CCH6. H Cl + H.S

:NC0Hfi

Thujeaihanilide.                       Pheiiyl Mustard     Triphenylguanidine

Oil.                  Hydrochloride.

Properties.—Colourless needles ; in. p. 143°.
Reaction. — Boil   for a  short   time  with   moderately  strong
caustic soda solution.    Aniline is formed.

See Appendix) p. 281.
PRKPARAT JN 62.                                :
Diazobenzene Sulphate. C-Hr-N.SCXH
III
N
(iriess, Anualen, 1866, 137, 76 ; Knocvcnagel, Bcr., 1895, 28,
2049.
15 gnus, aniline.
140   „      (175 c.c.) absolute alcohol.1
30   „      (16 c.c.) cone, sulphuric acid.
20   „      amyl nitrite.
Mix the aniline and alcohol and add the concentrated
sulphuric acid in a slow stream with constant shaking. The
precipitate of aniline sulphate, which first appears, reclissolves.
Cool the mixture to 30'' and keep at 30—35° (thermometer in
the liquid) and out of direct sunlight whilst the amyl nitrite is
dropped in from a tap-ftmnd. Then cool in ice water, and
leave for half an hour. The dia/obenzene sulphate separates as
a colourless or pale green mass of needle-shaped crystals.'** It-
is filtered at the pump and washed with a little alcohol.
Although diaxobenzene sulphate is much more stable 'than the
1 Neither methylated spirit noi' methyl alcohol can be substituted.
COHEN'S ADV. p. o. c.                                                M
PRACTICAL ORGANIC CHEMISTRY

nitrate, it is undesirable to let the precipitate become quite dry.
The various reactions described below are carried out witli
the slightly moist and well pressed precipitate.

Properties.—Colourless needles; soluble in water and
methyl alcohol ; slightly soluble in ethyl alcohol.
Reactions.—The following reactions are performed in test-
tubes with about a gram of the substance.
1.  Warm  the  substance with a few  c.c.  of ethyl  alcoliol.
Vigorous effervescence occurs and the liquid turns red.    Wlieii
effervescence ceases, add water.   An oil separates out on   tlie
surface consisting of benzene mixed with a little phenetol.
C0H5N0SO4H + C2H6O = C6HG + N2 + C2H4O + H9SO4
C0H3N3SO4H + C2H(JO = C6H5OC2H5 + N2 + H2SO4.
2.   Dissolve about a gram of the substance in a little water,
cool in  ice  and  make alkaline with  caustic  soda.    Make    an
alkaline solution of stannotts hydrate by dissolving 3—4 grams
of stannous chloride in twice its weight of water and adding'
strong caustic soda  solution  until the  precipitate redissolves.
Cool the diazo solution and add the alkaline stannous hydrate.
Effervescence occurs, nitrogen is liberated and benzene separates
on the surface of the liquid and can be detected by its smell.
C6H5N2. ONa + Sn(ONa)2 -I- HaO = C6Ha + N2 + Na2SnO:} + NaO 1I -
3.   Dissolve the substance in a few c.c. of cold water and axld
a solution of bromine in  potassium bromide  until  no  furtlier
turbidity is produced.    A black oil collects at the bottom of  the
test-tube.    Pour off the top layer as far as possible, and let   the
oil stand in cold water.   It .solidifies.   This is the perbromide of
diazobenzene.
C6H5N2SO,H + KBr + Br2=C0H5NBrNBr2 + KHSO4.
Decant any liquid and warm the perbromide with a little alcoliol.
Nitrggen and bromine are given off and bromobenzene is
formed.
CfcHfiNBrNBr2 = C6H5Br + N2 + Bi>
4.    Dissolve the  substance in a little  cold water and    add
TOLUENE FROM p-TOLUIDINE                  163
potassium iodide solution.    Effervescence occurs  and  a  dark
coloured liquid separates out.    This is iodobenzene.
C0HGN,S04H + KI = C0H6I + N2 + KHSO4.
5.    Dissolve the substance in water and warm gently.    Effer-
vescence occurs and a dark coloured oil separates, which has the
smell of phenol.    When effervescence ceases, cool and shake
up with a little ether.    Decant the ether into a dry test-tube.
Evaporate the ether and test the residue for phenol, see p. 179.
Cyif.NoSOJi + FLO = C0H5OH + H2SO4 + N2.
6.    Dissolve the substance  in cold water and add it to a
solution of phenol in caustic soda, drop by drop.    An orange
crystalline precipitate of hydroxyazobenzene is formed.    Repeat,
using /3-naphthol in place of phenol.    A scarlet precipitate is
obtained.
CGH6N,,SO.,H + C(5H,ONa - C0Hr,N:N.C0H4ONa + Na,SO4
-f 2NaOH                                          + 2H20.
7.    Dissolve in cold water and add a few drops of aniline,
and shake up.    Diazoaminobenzene separates out as a yello\v
crystalline precipitate.
C(iH5N,S04H + C0HSNH3 = C0HfiN:N.NHC0H5 + H2SO4.
8.    Heat o'5 gram of the dry substance on an iron tray.    It
decomposes with slight explosion.
Any of the diazo-compound which remains over should be
dissolved in water and poured away.    See Appendix^ p. 282.
PREPARATION 63.
Toluene from p-Tohiidine, C(iH-.CH3,
Kricclliindcr, Her., 1889, 22, 587.
10 I>TIYJS. /;-toluidinc.
30 c.c. cone, hydrochloric acid (in 60 c.c. water).
7-5 „   sodium nitrite (in powder).
15   „   of caustic soda (in 50 c.c. water).
30  „   stannous chloride (in 75 c.c. water).
The /Moluidine, which is placed in a beaker, is dissolved in
the hydrochloric acid by warming and is then cooled under the
M 2
164               PRACTICAL ORGANIC CHEMISTRY
tap, so as to obtain small crystals of the hydrochloride. The
beaker is placed in a freezing mixture and the contents cooled
below 10°. The sodium nitrite is added in small portions at a
time with stirring, the temperature being kept below 10°. The
hydrochloride gradually dissolves in the form of the soluble
diazonium salt. Towards the end of the operation a drop of the
solution is occasionally tested with potassium iodide and starch
paper when an excess of nitrite is indicated by a blue sta.hi.
The solution is poured very slowly into the solution of caustic
soda previously cooled in ice, so that the temperature does not
rise above 10°.
CH3.C6H4N2C1 + 2NaOH = CH3.C6H4N2ONa + NaCl + H2O.
Meantime the stannous chloride solution is converted into sodium
stannite by adding a 50 per cent, solution of caustic soda until
the precipitate of the hydrate nearly redissolves (about 30grams
of caustic soda). The liquid is placed in a round flask (500 c.c.)
attached to a condenser and cooled^in ice. The alkaline diazo
solution is poured through the top of the condenser in small
quantities at a time. After each addition there is a vigorous
effervescence and evolution of nitrogen,and a brown oil separates
which consists of impure toluene.
CH3CGH4NoONa + Sn(ONa)2 + H2O = CH3.C6H5 + No + NaoSnO.,
+ NaOH.
When the solution has all been added the toluene is distilled off
in steam, separated from the water, and dehydrated over calcium
chloride. It distils at 110°. Yield 5—6 grams.
p. 284.
PREPARATION 64.
p-Cresol, CG
Griess, Annalen, 1866, 137, 39; Ihle, /. prakt. Chem.^ 1876,
H 451.
25 grms. /-toluidine.
2-5     „    cone, sulphuric acid (in 750 c.c. water).
20     „     sodium nitrite (in 40 c.c. water).
Mix the dilute sulphuric acid and toluidine in a large round
flask (ij litre) and cool to the ordinary temperature. The nitrite
p-CIILOROTOLUENE

solution is gradually added. The clear solution is then gently
warmed on the water-bath until the evolution of nitrogen ceases.
The solution, which has become very dark coloured, is distilled
in steam until the distillate produces only a slight precipitate
with bromine water (500 c.c.). A small quantity of tarry residue
remains. The distillate is then extracted three times with small
quantities (50 c.c.) of ether. The ethereal solution is dehydrated
over anhydrous sodium sulphate, filtered, and the ether removed
on the water-bath. Thc/-cresol is then distilled over the flame
with a condenser tube, and collected at 195—200°. The distil-
late, which has a yellow colour, solidifies on cooling. Yield 10
— 15 grams.

4-2N2~KNa,S(),,~h211/3.
Properties.— Colourless crystals ; in. p. 36° ; b. p. 202°.
Reactions.—Make a solution of //-crcsol by shaking up a
few drops with 5 c.c. of water. To one portion add a few drops
of bromine water. A white precipitate of tetrabromocrcsol
is formed. To another portion add a drop of ferric chloride.
A blue colouration is produced. See Appendix^ p. 284.
PREPARATION 65.
p-Chlorotoluene,    CnH.l</£1H-<» l
Sandmcyer, Tfcr., 18(84, 17, 2651 ; Wynne, Trans. Chcm. Soc.,
1892,61,1072.
50 grins./-toluicline.
120 c.c. cone, hydrochloric acid (in So c.c. water),
40 grins, sodium nitrite (coarsely powdered).
30    „      copper carbonate to be dissolved in 300 c.c. cone.
hydrochloric acid
Dissolve the /-toluidine in the hydrochloric acid and then
cool, quickly in a beaker, and stir so as to obtain small crystals.
Place the beaker in ice and salt and, whilst it is cooling,
prepare a solution of cuprous chloride. Dissolve the copper
carbonate in the hydrochloric arid, and boil with excess of
copper turnings until a nearly colourless solution is obtained.
The solution is decanted into a large round flask (2 litres)
166               PRACTICAL ORGANIC CHEMISTRY

which is loosely corked, and placed in ice. Whilst triis
solution is cooling to o° the diazotoluene chloride is prepared
by adding the powdered sodium nitrite gradually to the j>-
toluidine hydrochloride and stirring. The temperature sliould
not rise above 10°. When three-quarters of the nitrite has l>een
added, test occasionally with potassium iodide-starch paper until
a drop gives an immediate deep blue or dark brown colouration.
Add this solution gradually in portions of about 20 c.c. at a. time
to the cold solution of the cuprous chloride, and shake up well
after each addition. A thick crystalline mass of orange coloured
needles, consisting probably of the diazo-copper salt separates,
and, on standing, decomposes slowly, forming a dark-coloured
liquid. After standing a short time, the liquid is distilled in stoa.m.
The distillate is shaken up with a little caustic soda to remove
cresol, and the chlorptoluene, which sinks to the bottom, is
separated. The liquid is further shaken out with a little chloro-
form, which is then added to the chlorotoluene, and the \vliole
dehydrated with calcium chloride. The liquid is decanted, the
chloroform distilled off and the residue collected at 115 - 165°.
Yield, about 45 grams.

2O.
CH3CCH4N2C1 = CH3CGH4C1 + N J
Properties. — Colourless liquid ; b. p. 162° ; m. p. 7*4
Reactions.— Chlorobenzoic Acid. — Boil 10 grams ^-
toluene with 20 grams permanganate dissolved in 500 c.c. of writer
in a brine or calcium chloride bath, with upright condenser, for a
day. The bath should keep the contents of the flask too i ling'
briskly whilst the permanganate is gradually added. Trie oily
drops of chlorotoluene will gradually cease to drip from tlio con-
denser and the permanganate will be nearly decolourised.
The precipitated manganese dioxide is now dissolved a.s sul-
phate by passing in sulphur dioxide gas until the last trace of
brown precipitate has disappeared. The colourless criloro-
benzoic acid comes down in the acid solution on cooling*, and
is filtered, washed with water, and recrystallised from Sjpirit ;
m. p. 236°. The yield is theoretical.
CH3.C6H4C1 + 03 = COOH. C6H4C1 + H2O.
See Appendix, p. 284.
p-BROMOTOLUENE                            167

PREPARATION  66.

p-Bromotoluene, CGH,<
4
Sanclmeycr, Ber., 1884,17,2651 ; Gattermann, Ber., 1890,28,
1218.
50 grins, /-toluidine.
100 c.c. cone, hydrochloric acid (in 60 c.c. water).
35 grins, sodium nitrite (in powder).
9°     «     crystallised copper sulphate (in 300 c.c.water).
45     „     potassium bromide (in 100 c.c. water).
150 c.c.   hyclrobromic acid (sp. gr. 1-49 = 47 per cent. HBr).
The ^-loluidinc is diazotiscd as described in the previous experi-
ment (Prep. 65) by forming- the hydrochloride, cooling and
gradually adding" the sodium nitrite. The solution of the
diazonium chloride is then poured into cuprous bromide dis-
solved in hyclrobromic acid. The cuprous bromide is prepared
by adding the potassium bromide solution to the copper sulphate
solution and passing in sulphur dioxide until no more precipitate
forms-. The white cuprous bromide (about 35 grams) is filtered,
washed, and well pressed on the funnel and introduced into a
round flask (i .1 litre). It is dissolved in 150 c.c. hyclrobromic acid
and well cooled in ice. The diazonium chloride is now added
slowly with constant shaking. A thick pasty mass separates and
nitrogen is evolved. When the evolution of gas has slackened
the flask is heated on the water-bath until effervescence ceases
and the bromotolucnc is then distilled in steam. The heavy
yellow liquid is extracted with chloroform, shaken with caustic
soda solution to remove traces of cresol, dehydrated over calcium
chloride, and distilled. The distillate is collected at 180—190°
On cooling, it solidifies to a pale yellow mass, m. p. 28°; b. p.
185°. Yield, 35 grams.
CI I.j.QH.t N,C1 + CuBr = CH3.C0H4Br + CuCl 4- N2.
Gattermarm's Method.—According to this method the
diazonium bromide is first prepared and then decomposed by
finely divided metallic copper. The 50 grams /-toluidine is
dissolved in 200 c.c. hyclrobromic acid previously diluted with
100 c.c. water and diazotised in the usual way. To this solution
fi



i6s \         PRACTICAL ORGANIC CHEMISTRY
the copper powder is gradually added. It is prepared by dis-
solving 100 grams crystallised copper sulphate in 300 c.c. water
and dusting in through a fine muslin bag 25 grams zinc dust with
constant stirring. It is left until the blue colour of the copper
salt has nearly disappeared. The precipitated powder is washed
' •";                      by decantation two or three times with cold water and then with
very dilute hydrochloric acid to remove metallic zinc and
finally filtered and washed at the pump. The pasty mass is not
allowed to dry, but is added at once in small quantities to the
diazonium solution with constant stirring. After the evolution
of nitrogen has ceased the bromotoluene is distilled in steam
and purified as described above. See Appendix^ p. 284,
PREPARATION 67.
p-Iodotoluene.
Griess, Annalen, 1866, 137, 76.
25 grms. /-toluidine.
50   „     (27 c.c.) cone, sulphuric acid (in 250 c.c. water).
20   „     sodium nitrite (in 40 c.c. water).
60   „     potassium iodide (in 100 c.c. water).
Mix the dilute sulphuric acid and /-toluidine in a larg-e
beaker (f litre) and cool to o° in a freezing mixture. Stir,
whilst cooling, to produce small crystals of the sulphate. Axlcl
the solution of sodium nitrite slowly, and if the temperature
rises above 10°, add a few lumps of ice. When three-quarters
of the nitrite solution has been added, test occasionally with
potassium iodide-starch paper until a blue or brown stain is
produced. Now add the solution of potassium iodide gradually,
and, after well stirring, leave the mixture at the ordinary temper-
ature for an hour, and then warm cautiously on the water-bath
until effervescence ceases. The liquid is dark coloured, and a
black oil settles to the bottom of the vessel, which when cold
solidifies. The oil consists of iodotoluene, and the dark colour of
the solution is due to free iodine, which may be removed by the
addition of a gram or two of sodium- bisulphite. The mixture
is now distilled in steam, using a beaker as receiver. Care must
, |                    be taken to prevent the condenser tube becoming blocked by the
|                      iodotoluene, which is solid at the ordinary temperature.    This is
JLYLCYANIDE

effected by running the water very slowly through the condenser
so that the upper part remains warm. Theiodotoluene solidifies
in the receiver. It has a yellow tint, which may be removed by
recrystallisation from spirit. Yield, 45—50 grams.

NaHSO4+HoO.
CH3.C(5H1N,,SO,H + KI = CH,.C«H4I + N2+ KHSO4.
Properties.—-Colourless plates ; m. p. 35° ; b. p. 211—212°.
1.  Tolyliodochloride.—Dissolve TO grams iodotoluene in
five times its weight of chloroform, cool in ice, and pass in dry
chlorine until saturated.    If a chlorine cylinder is not available,
the chlorine  is  conveniently made by dropping concentrated
hydrochloric acid from a tap-funnel on to powdered potassium
bichromate or permanganate in a round flask, heated on the
water-bath.    The    chlorine    is    dried   through    concentrated
sulphuric   acid.    When   chlorine   is   no   longer absorbed, the
yellow needle-shaped crystals of the ioclochloride are filtered,
washed with a little chloroform, and dried on a porous plate.
CH3.C0H4I + C13= CH3.CaH4ICl2.
2.  lodosotoluene.—Dissolve 2-5 grams caustic soda in 20
c.c. water, and grind with 5 grams of iodochloricle in a mortar.
Leave  overnight and  then  filter and wash with water.    The
colourless crystals of the iodoso-compound are dried on a porous
plate.
CIl;,C(;H.llCl.H-2Na()H = CH;t.CtiHJO + 2NaCl + H2O.
See Appendix, p. 285.
PRKPARATION 68.
/CM,    i
p-Tolylcyanide, C,.!!,^
X:N   4
Sandmeyer, />Vr., 1884, 17, 2653.
20 grins, /-toluidine.
45 c.c. cone, hydrochloric acid (in 150 c.c. water).
16 grins, sodium nitrite (in 40 c.c. water).
50    „    copper sulphate (in 200 c.c. water).
55     „    potassium cyanide (in 100 c.c. water).
The copper sulphate is dissolved  in 200. c.c. water on the
water-bath in a round flask (2 litres).    Pure potassium cyanide
I7o              PRACTICAL ORGANIC CHEMISTRY

is gradually added to the warm solution.*1 The cuprous cyanide
dissolves in excess of the potassium cyanide and cyanogen g'as
is liberated. 2CuSO4 + 4KCN = 2CuCN + 2K2S04 + (CN)2-
The solution is left, whilst the /-toluidine is diazotised.
The base is dissolved in the dilute hydrochloric acid, cooled, in
ice, and well stirred. The mixture is kept cold whilst the sodium
nitrite solution is gradually added, until it gives an immediate
colouration with potassium iodide-starch paper. The clia-zo-
solution is then added in portions of about 10 c.c. at a
time to the warm cuprous cyanide solution, with frequent
shaking. A rapid effervescence occurs, nitrogen and some
hydrocyanic acid being evolved. When, in the course of a/bout
fifteen minutes, the diazo-solution has been added, it is left
on the water-bath until effervescence ceases (J hour). The
liquid turns a dark colour, and a black tarry deposit is
formed. The product is distilled in steam. This should be
carried out in the fume cupboard, as not only is hydrocyanic
acid liberated, but a small quantity of isocyanide, which is formed
inthe reaction, and produces an intolerable smell. The distillation
is continued until no more yellow oil passes over. The tolyl
cyanide solidifies in the receiver on cooling as a yellow crystal-
line mass, which is filtered, dried on a porous plate, and may be
purified by distillation ; but for the preparation of toluic acid
this is unnecessary. Yield about 15 grams.

CH3.C0H4NHo.HCl + NaN02+ HC1 = CH3.CflH4N2CHh

Properties.— Colourless crystals ; m. p. 29° ; b. p. 218°.

Reaction. — p-Toluic Acid. — Boil up 10 grams tolylcyanide
with a mixture of 30 c.c. cone, sulphuric acid and 20 c.c. water, in a.
round flask with upright condenser until colourless crystals of
toluic acid appear in the condenser tube (about half an hour). On
cooling, the acid crystallises out, and is separated by filtration,
washed with water, and recrystallised from hot water ; m. p. I 79°.

CH3.CGH4.CN + 2HoO -1- H9S04 = CH3.C6H4.CO.OM
+ NH4.H.SOi.

if    |                       The yield is nearly theoretical.
DIAZOAMINOBENZENE                       171

Terephthalic Acid.—Dissolve 5 grams/-toluic acid in dilute
caustic soda solution and boil with reflux condenser, adding 12
grams of permanganate in 250 c.c. water gradually from a tap
funnel inserted through the top of the condenser. When the red
colour of the permanganate persists after continued boiling the
solution is treated with sulphur dioxide (see p. 166), which dissolves
the manganese dioxide and precipitates the terephthalic acid as
a white amorphous powder. The latter is filtered, washed, and
dried. It sublimes without melting at 300'' and is insoluble in
water and alcohol. The yield is nearly theoretical.
CII3.C0H4.COONa+NaOH + 2KMnO4==
NaOOC.CGH4.COONa + 2KOH + MnO2 + 2H2O.
PREPARATION 69.
Diazoamiiiobenzene, C0H5N :N.NH.CBH5.
Gricss, Annalcn, 1866, 137, 58 ;  Staedel, Bauer, Ber., 1886, 19,
1952.
20 grms. aniline.
6     „    cone, sulphuric acid.
600     „    water.
7*4     „    sodium nitrite.
The acid is poured into the water contained in a large beaker
(i litre) and the aniline then added. About half the aniline
dissolves as sulphate. The liquid is warmed in the water-bath to
27^and the sodium nitrite, dissolved in a small quantity of water,
is slowly added and the whole well stirred. The temperature
is maintained at 27—30° for a quarter of an hour. As soon as
the sodium nitrite is added the liquid turns yellow and rapidly
becomes turbid from the formation of diazoaminobenzene,
• which separates out in yellowish brown crystalline crusts. The
solution is now allowed to stand at the ordinary temperature
for half an hour, when nearly the whole of the diazoarnino-
bcnzene crystallises out. It is filtered, washed with cold water,
pressed well on the filter, and dried on a porous plate or a pad
of filter paper. It forms a brown sandy powder and may be
purified by recrystallisation from benzene or alcohol. In
crystallising, it is necessary to bring the substance into solution
as quickly as possible. Boiling spirit (about three times the
172               PRACTICAL ORGANIC CHEMISTRY
weight of substance) should be added and the liquid heated for
a moment until a clear solution is obtained and then allowed to
cool. On prolonged boiling it decomposes. For the preparation
of aminoazobenzene the dry powder is sufficiently pure. Yield,
nearly theoretical.
(C6H5NH9)oH2SO4 + 2NaNO2 + 2H2SO4 =
2C0H5N2.SO4H + Na2SO4 + 4H2O.
CGH5N2.S04H + CCH5NH2 = C8H6N:N.NHC6H5 + H2SO4.
N.B.—The sulphuric acid, set free in the second phase of the reaction,
acts upon the sodium nitrite, so that one molecule only is required.
Properties.—Golden yellow plates (from alcohol) m. p. 98° ;
insoluble in water; it explodes when heated above its melting"
point.
Reaction.—Dissolve a little of the substance in alcohol and
add a drop or two of an alcoholic solution of silver nitrate. A
red crystalline precipitate of C6H6N:N.NAg.C6H5 is deposited.
See Appendix, p. 285.
PREPARATION 70.
Aminoazobenzene (Aniline yellow), C0H5N:NC0H4NI-l2-
Mene,/£/m^., 1861, 496; Kekule', Zeitsch.f. CA., 1866, 2, 689 ;
Staedel, Bauer, Ber., 1886, 19, 1953.
10 grms. diazoaminobenzene.
25    „      aniline.
5    ,,      aniline hydro-chloride.
The finely powdered diazoaminobenzene, aniline hydro-
chloride (see p. 156), and aniline are mixed together and heated
to 40° for an hour. The mixture forms a clear, deep red solution.
After standing for 24 hours at the ordinary temperature, the
diazoaminobenzene is converted into aminoazobenzene. A,
slight excess of moderately strong hydrochloric acid is added,
care being taken that no great evolution of heat occurs. On
cooling, the aminoazobenzene separates out together with
aniline hydrochloride. It is filtered and washed with cold, very
dilute hydrochloric acid, when small violet crystals of aminoazo-
benzene hydrochloride remain on the filter. In order to obtain,
the free base, the hydrochloride is warmed with dilute ammonia.
I

PHENYLHYDRAZINE                           173
The base, which has a brown colour, is filtered and dissolved
in hot spirit, with the addition of a few drops of concentrated                      «
ammonia.    Yield, about 8 grams.
C0H6N:N.NHC0H6 + H.C0H4NH2.HC1 -
C0H5N:N.C0H4.NH2 + CCH5NH2.HC1.                        I
Properties.—Orange prisms ; m. p. 127°.                                                       , J
Reaction.—Make a solution of 4 grams stannous chloride in
10 c.c. cone, hydrochloric acid, add 2 grams aminoazobenzene,                       J»'
and boil for a few minutes.    On cooling crystals of the hydro-                      /
chlorides  of   aniline   and  ^-phenylenediamine  separate   out.                      1
The  liquid  is filtered  and  washed with a little cone, hydro-                      ;" j,
chloric  acid  to  remove  the  tin salts.     If the   precipitate   is                       ' \>
dissolved  in  water  and   made alkaline with  caustic soda, a                       '*
mixture of liquid aniline and solid/-phenylenediamine is pre-                       \
cipitated, from which the former may be removed by filtering,
washing, and draining on a porous plate.                                                          ^;
C0HBN:N.C0H4NHo + "2SnCl2 + 4HC1=                                                          />
C0H5NH2 4- H2N.CGH4.NH2 + 2SnCl4.                           '*
/-Phenylenediamine, when warmed with dilute sulphuric acid                        ''
and potassium bichromate or lead peroxide, gives the odour of                        ji
quinone (p.-192).    After warming and cooling, extract with ether.                       flL
The ethereal solution has a yellow colour.    Decant the ether                       1p
extract on to a watch-glass and leave it to evaporate in the air.                       'ft
A deposit of microscopic yellow crystals remains.    See Appen-                      * ,,
diX) p. 286.                                                                                                        ||*
**\
PREPARATION  71.                                                   ^
Phenylhydrazine, C0H5NH,NH2                                        -,f
E.  Fischer, Annalen,   1878, 190, .167 ; Meyer, Lecco,   Ber^                      \\. '
1883, 16, 2976 ; Meyer and Jacobson, Lchrlntch, 2, 305.                           ^
20 grms. aniline.                                                                                !\ ^
200 „ (170 c.c.) cone, hydrochloric acid.                                         ' *
20 „ sodium nitrite (in 100 c.c. water).                                        ^
120 „ crystallised stannous chloride (in  100 c.c. ^
cone, hydrochloric acid). .                                           ?;'
1 |f*
The  aniline is dissolved  in  the  concentrated hydrochloric                       k\(
acid and cooled to o° in a freezing mixture.    The solution of                     ' i (.
I74    '          PRACTICAL ORGANIC CHEMISTRY

" sodium nitrite is gradually added, the temperature being kept
below ioc, until a drop of the mixture, diluted with water, turns
potassium iodide-starch paper blue. To the mixture, still cooled
in ice, 120 grams stannous chloride, dissolved in about an
equal weight of cone, hydrochloric acid, is added. A thick
white crystalline precipitate of phenylhydrazine hydrochloride
separates. It is allowed to stand for half an hour and filtered at
the pump ; it is then separated as far as possible from the mother
liquor, and transferred to a flask. The free base is obtained by
decomposing the hydrochloride with caustic socla. An excess
of caustic soda is added, and the mixture well shaken. The
free base, which separates as a reddish coloured oil, is extracted
with ether, and the ethereal solution dehydrated over solid
potassium carbonate. The ether is then removed on the water-
bath, and the residual oil either used without further purification
or distilled in vacua. Yield, 1 5 — 20 grams.

C0H5N H2. H Cl 4- NaN O2 + H Cl = CGH5N,. Cl +

2O.

Properties. — Nearly .colourless oil when freshly distilled ;
b. p. 241—242° ; m. p. 17-5° ; sp. gr. 1-097 at 23°.
Reactions. — i. Add a few drops of phenylhydrazine to 2 c.c.
of water, then a drop or two of copper sulphate solution and
excess of caustic soda. Cuprous oxide is precipitated with
effervescence and benzene separates, C0HsNH.NH2 + 2CuO —
C6H0+N2+Cu2O + H2O. The same reaction takes place if
the phenylhydrazine is dissolved in dilute acetic acid and copper
sulphafte solution added and warmed.
2.  Add 2 grams of phenylhydrazine to 4 c.c. water in a boiling-
tube, warm until dissolved, and then add about 3 c.c. of a warm
saturated solution of cupric hydrate dissolved in cone, ammonia.
Nitrogen is evolved and cuprous hydroxide dissolves.    Add a 10
per cent, caustic potash solution until there is a slight permanent
precipitate  of cuprous hydroxide and heat the liquid  in   the
water-bath.    A copper mirror is .deposited on the surface of the
glass (Chattaway).
3.  Add to a few drops of phenylhydrazine an equal quantity
of glacial  acetic  acid,  dilute  with a  little water, and a1:ld a
SULPHANILIC ACID                          175

drop of benzaldehyde. In a short time the phenylhydrazone of
benzaldehyde will crystallise out.                                                                  I

4. Plienylmethylpyrazolone.— Mix together 10 grams dry                   ;

phenylhydrazine hydrochloride*ancl 9 grams acetoacetic ester in a
flask (200 c.c.), add 3 or 4 drops cone, hydrochloric acid and
warm for 10 — 15 minutes.- A clear reddish solution is obtained,                        , jf

which is poured into water and carefully neutralised with caustic                         (

soda.     The precipitated oil solidifies almost immediately and                        ;',

can be recrystallised from alcohol ; m. p. 127°.    Yield 8 grams.                        !

!             CH3.C CH2.CO                                        { ,

j-4-H2O + C2H5OH.
See also the Reactions on pp. 70, and   135, and Appendix,
p. 287.
\. PREPARATION 72.
x':~"                                 /NH2    i
Snlphanilic Acid, C6H4<;
\S03H     4
Gerhardt, Annalen, 1846, 60, 312 ; Buckton, Hofmann,
Annalen, 1856, 100, 163.
25 grms. aniline.
80    „     cone, sulphuric acid.
The aniline and sulphuric acid are cautiously mixed in a '
round flask (250 c.c.) and heated to 180—190° in an oil or metal
bath for four to five hours until a sample dissolved in water
remains clear on the addition of caustic soda in excess and no
aniline separates. The product is poured into cold water, which
precipitates the sulphanilic acid as a grey crystalline mass. «' It
is filtered, washed with a little cold water, recrystallised from
hot water with the addition of a little animal charcoal, and dried
in the air. Yield, 25—30 grams.
CCH5NH2 + H2SO4-= NH2.CGH4.S03H 4- H2O.
Properties. — Colourless rhombic plates, containing 2 mols. of
water of crystallisation, which they lose slowly in the air, and
the crystals fall to powder. See Appendix^ p. 289.
i;6              PRACTICAL ORGANIC CHEMISTRY
PREPARATION  73.
Methyl Orange (Helianthin), SO3Na.C0H4N-:N.C0H4N(CH3)3
10 grms. sulphanilic acid.
2*5   „    anhydrous sodium carbonate (in 100 c.c. water).
3-5   „    sodium nitrite (in 20 c.c. water).
6  „     cone, hydrochloric acid (in 10 c.c. water).
6  „    dimethylaniline  (in 6 c.c. cone. HC1 and 20   c.c.
water).
The sulphanilic acicl is dissolved in the sodium carbonate
(£ mol.) solution and the sodium nitrite (i mol.) solution added.
The mixture is cooled in ice, and the solution of hydrochloric
acid (i mol.) gradually added. The solution of dimethylaniline
(i mol.) is now poured in, and the liquid made alkaline with
caustic soda. The separation of methyl orange at once begins,
and is assisted by the addition of a little common salt (20 grains).
The precipitate is filtered at the pump, and crystallised from
hot water. Yield, nearly theoretical.
S03Na.C0H4NH2 4- NaNO2 + 2HC1 = SO3Na.C0H4N2.Cl H-
NaCl + 2H2O.
S03Na.QH4N2.Cl + CflH6N(CH3)3HCl ==
SO3H.CCH4.N2.C6H4N(CH3)2 + NaCl + HCL
S03H.C0H4N:N.C0H4N(CH3)2 + NaOH =
SO3Na.C6H4N:N.C6H4N(CH3)2 + H2O.
Properties.—Methyl orange is the sodium salt of the sul-
pl^oic acid, and dissolves in water with a yellow colour. Tlie
friracid is red, and its action as an indicator depends upon
this change on the addition of mineral acid.
Reaction.—Methyl orange is decomposed, like the majority of
azo-compounds, by stannous chloride in hydrochloric acicl Into
molecules, produced by the addition of hydrogen to tlie
Double-linked nitrogen atoms (see p. 173).
HS03.C6H4N:N.CG-H4N(CH3)0 4- 2SnCU + 4HC1 =
HS03.C6H4NHo + HoNC0H4N(CH3)2 + 2SnCl4.
IT
POTASSIUM BENZENE SULPHONATE             177

Make a solution of 4 grams stannous chloride in 10 c.c. cone,
hydrochloric acid, add I gram of methyl orange dissolved in a
few drops of hot water, and boil for a few minutes until the red
colour disappears. On cooling a crystalline precipitate consist-
ing of sulphanilic acid and dimethyl /-phenylenediamine is
deposited. In order to separate the base, dilute with water, add
caustic soda solution until the precipitate of stannous hydrate
redissolves, shake out the cold solution with ether, and de-
hydrate over potassium carbonate. On distilling off the ether,
the dimethyl /-phenylenediamine remains as a crystalline
solid ; m. p. 41°, On warming with dilute sulphuric acid and
lead peroxide the odour of quinone is readily perceived
(see p. 192). It also gives the (methylene blue' reaction, like
nitrosodimethylaniline (see p. 158). See Appendix, p. 289.

PREPARATION 74.
Potassium Benzenesulphonate, C6H5.SO3K + iH2O
Mitscherlich, Pogg. Ann., 1834, 31, 283 and 364; Michael,
Adair, Bar., 1877, 10, 585.
60 c.c. benzene.
60   „   cone, sulphuric acid.
The benzene and sulphuric acid are heated together on a
sand-bath in a round flask (•£ litre) with upright condenser.
The mixture is kept at a gentle boil with frequent shaking (an
apparatus like that shown in Fig. 78, p. I475 with mechanical
stirrer is preferable) until the top layer of benzene has Jpeen
nearly absorbed by the sulphuric acid (six to eight hours)/" On
cooling, the dark-coloured liquid is poured into cold water
(t litre) contained in a large basin, boiled up and neutralised
with powdered chalk or thick milk of lime. The massjs                       Jp
filtered'hot through a porcelain funnel or cloth from the ]|re-                      |
cipitate   of calcium   sulphate,   washed   with   hot   water   and                       J
somewhat concentrated. The solution, which contains the
calcium salt of benzene sulphonic acid, is treated with just
sufficient potassium carbonate solution to precipitate the calcium                      |! |
as carbonate and convert the sulphonic^acid into the potassium                      l||
COHEN'S ADV, p. o. c.                                               N
i78              PRACTICAL ORGANIC CHEMISTRY

salt. This is ascertained by filtering small samples and testing
the filtrate with potassium carbonate. The liquid is ag-ain
filtered through cloth or through a porcelain funnel and concen-
trated first over a ring burner, and finally on the water-bath,
until a sample crystallises on cooling. The potassium salt is
drained at the pump and dried on porous plate. Yield, about
80 grams.

CGHG + H2S04 = CGH5S03H + H2O.

2CGH5S03H + CaC03=(CcH3SOs)2Ca + C02 + H2O.
(C0H6S03)3Ca+K2C03=2C6H5S03

Properties. — Colourless pearly plates, which slowly effloresce
in the air and which melt above 300° with slight decomposition ;
very soluble in water. See Appendix^ p. 292.

PREPARATION 75.

Benzenesnlphonic Chloride, C0H3SO2C1
Gerhardt, Chiozza, Annalen, 1853. 87, 299.

1 5 grms. potassium benzene sulphonate.
25    „     phosphorous pentachloride.

The potassium benzenesulphonate is carefully dried on the
water-bath, powdered, and mixed with the phosphorus penta-
chloride in a flask.* A vigorous reaction sets in. When it has
abated, the flask is heated on the water-bath for one hour,*
and the mass occasionally stirred with a glass rod. The pro-
duct is poured into a flask containing 200 c.c. cold water and
allowed to stand an hour. The sulphonic chloride, which
separates as an oil, is then extracted with ether, dehydrated
over calcium chloride, decanted, and the ether removed on the
water-bath. Yield, 10 grams of a light brown oil.

Properties. — Colourless oil when pure ; b. p. 246 — 247°  witli
decomposition ; m. p. 14° ; distils undecomposed in vacua.
PHENOL

179

Reaction. — i. Grind up in a mortar I c.c. of sulphonic chloride
with 5 grams powdered ammonium carbonate, and leave on the
water-bath until the smell of the sulphonic chloride has gone.
Add water, filter, and wash, and crystallise the residue of
benzene sulphonamide from spirit, CCH5SO.>C1 + 2NH4HCO3 =

2.  Add I c.c. of the sulphonic chloride to 2 c.c. aniline, stir
up well, add water, and acidify with a few drops of concentrated
HC1  (methyl violet  paper).    Filter,  wash, and crystallise  the
benzenesulphonanilide   from   spirit,   CGH3SOoClH-NH.,C0Hr •=
CGH5S02NHCCH5+HC1.
3.  Add 2 c.c. absolute alcohol to i c.c. sulphonic chloride and
excess  of caustic  soda until  alkaline ; warm  gently for five
minutes and add more caustic soda if necessary.    Cool, and
extract with ether.    The residualliquid consists of benzene ethyl
sulphonate, C0H5SO2Cl-fHOC2H5=C6H5SOoOC2H5-l-HCL
4.   Repeat 3, using phenol in place of alcohol.    See Appendix^
P- 293-
PREPARATION 76.
Phenol (Carbolic acid, Hydroxybenzene), CGH5.OH
Kekule, Wurtz, Dusart, Zcitschr. f. Ch. N.  F.,   1867,   3,
299-301 ; Degener, J.prakt. Chim. 1878, (2), 17, 394.
20 grins, potassium benzenesulphonate.
35    „      caustic potash.
The caustic potash is dissolved in the smallest quantity of
water (5 c.c.) by heating in a silver or nickel basin or crucible,
and the powdered potassium benzenesulphonate added. The
temperature of the melt, which during the process is kept con-
stantly stirred, must not exceed 250°. It is convenient to use
the thermometer as stirrer, the bulb and part of the stem being-
encased in a glass tube closed at one end. When the requisite
temperature has been reached, a small flame is sufficient to
maintain it. The mass is first thick and:. pasty, but soon be-
comes semi-fluid and remains in this condition, gradually
changing in colour from yellow to brown. Towards the end of
the operation (one hour) it regains somewhat its original con-
sistency. On cooling, the melt is dissolved in a little water
N  2
i8o              PRACTICAL ORGANIC CHEMISTRY

and the alkaline reddish-brown liquid (potassium phenate and
excess of alkali) acidified with concentrated hydrochloric acicl in
the cold. Phenol separates out as a light yellow oil, which is
extracted three times with ether. The ethereal solution de-
hydrated over anhydrous sodium sulphate is distilled, first on
the water-bath until the ether is removed, and then over the
flame. The portion boiling at 175 — 185° is nearly pure phenol.
It distils as a colourless liquid and solidifies at once on cooling.
Yield, 6—7 grams.

C0H6OK+ HC1 = CGH5OH + KC1.

Properties. — Colourless needles, with a characteristic smell ;
m. p. 42—43° ; b. p. 182° ; easily soluble in alcohol and ether ;
and in about 15 parts of water at the ordinary temperature ;
produces blisters on the skin.

Reactions. — i. Make a solution of phenol in water, and to one
portion add a drop of ferric chloride. A violet colouration is
produced.

2.  Add to another portion a drop of bromine water.   A white
crystalline precipitate of tribromophenol is formed.

3.  To a third portion add an equal volume of dilute ammonia
and a few drops of sodium hypochlorite and warm gently.     A
copper-sulphate-blue colour is produced.

4.  Add a small fragment of solid sodium nitrite to 5 c.c. concen-
trated sulphuric acid and warm very gently until dissolved.     On
adding about 0*5 gram of phenol, a brown solution is obtained,
which rapidly changes to deep blue.    If the blue solution  is
poured into water, a cherry red colouration is produced, which
changes to blue on the   addition of an alkali  (LiebeVmann's
'nitroso J reaction, see p. 159).

5.  Mix I gram of phenol with i c.c. of dimethyl sulphate l
and add 4 c.c. of a 10 per cent, solution of caustic    soda.
Warm and shake.   The odour of phenol is replaced by that of
anisole,   which can be   extracted   from   the   liquid hy    ether
(Ullmann's reaction).    See Appendix, p. 294.

1 The vapour of dimethyl sulphate is very poisonous, and care should   be  taken
not to breathe it.
ANISOLE                                     181

PREPARATION 77.

Anisole (Methyl phenate, Phenyl methyl ether), CGH5.O.CH3
Cahours, A?malen^ 1851, 78, 226.

5 grms.   sodium.

100 c.c.       methyl alcohol,

20 grms.   phenol.

40     „      methyl iodide.

The methyl alcohol is poured into a round flask (250 c.c.)
connected with an upright condenser. The sodium, cut into
small pieces, is then added, the flask being detached from the
condenser for 'a moment and replaced. When the sodium has
dissolved, the phenol and methyl iodide are added. The mixture
is heated on the water-bath until the solution has no longer an
alkaline reaction (two to three hours). As much as possible of
the methyl alcohol is distilled off on the water-bath and water
added to the amber-coloured residue. A colourless oil separates
out, which is extracted with ether. The ethereal solution is
dehydrated over calcium chloride and distilled, first on the
water-bath until the ether has been driven off, and then over
the flame. Almost the whole of the residue distils at 150 — 155°.
Yield, nearly theoretical.

Properties. — Colourless liquid, possessing an agreeable smell ;
b. p. 154° ; sp. gr. o'99i at 15°. See Appendix, p. 294.
>
PREPARATION  78.
Hexahydrophenol (Cyclohexanol), C0H11.OH
Sabatier and Senderens, Compt. rend.) 1901, 132, 210.
50 grms. phenol.
The phenol is reduced with hydrogen in presence of finely
divided metallic nickel ; which acts as a catalyst. The
apparatus is shown in Fig. 79.
182

PRACTICAL ORGANIC CHEMISTRY

It consists of an oblong Lothar-Meyer air-bath about 60 cms.
(241115.) long and 15 cms. ( 6 ins.) wide. It is heated on each side
by a series of small gas jets made by perforating an iron pipe
which runs below the air-bath. The hot air passes up the
space between the outside metal casing and an inner rectangular
metal box, and then clown and into the interior of the air-bath
through a number of round holes at the bottom of a central

v   !
V

<--------------60 cm.-------------•>

FIG. 79.

rectangular chamber, and finally escapes through a series of
holes in top of the outer cover. The air-bath is perforated.
at both ends so as to admit a piece of wi'de glass tubing. This
tubing (1*5—2 cms. diam.) is of such a length that it projects
about 2—3 cms. at one end and 5-6 cms. at the other, the latter
being bent and connected to a receiver. The shorter end is
attached by a cork to a small distilling flask through which, a.
current of dry hydrogen is passed from a Kipp by a delivery
tube, which reaches to the bottom of the flask.
o- AND p-NITROriIKNOL

183

Small pieces of pumice impregnated with a paste of nickel
oxide (NiO) and water is dried on the water-bath and packed into
the wide tube, which is then loosely plugged at each end with
asbestos. The phenol is incited and poured into the distilling flask.
The air-bath is slightly tilted so that any liquid which may collect
in the tube can run down into the receiver. The process is
conducted as follows : the delivery tube from the Kipp is first
raised above the surface of ihc phenol and a slow current of
pure dry hydrogen passed through the apparatus, the tempera-
ture of which is maintained at 300° for 20 minutes. The nickel
oxide is thereby reduced and changes from black to pale yellow.
After reduction, the lemperiture is lowered to 160-170° and
kept at this point. The phenol in the llask is now melted and
heated just below its boiling-point, whilst a fairly rapid current
of hydrogen is passed through the delivery tube, which is
thrust well into the liquid. The hcxahydrophcnol slowly distils
and condenses in the receiver. Care must be taken that the
phenol does not condense in the tube, but that only the vapour
passes over. When sufficient liquid has collected, it is shaken
with caustic soda solution, extracted with ether, dehydrated over
potassium carbonate and distilled.

C,,nf,OII + 6H =CtfHnOH.

Properties.-- Colourless liquid ; b. p. 170° ; pleasant aromatic
smell distinct from phenol; insoluble in water and solutions of
caustic alkalis. See Appendix, p. 295.

PREPARATION 79.
o- and p-Nitrophenol, C(iH,,<

•OH   i    i

Hofmann,  AnimlMJ, 1857, 103, 347 ; Fritsche, Aunalen, 1859,
110, 150 ;  Kekule, Lehrbitch d. org. chcm., 3, 40.
40 grins, phenol
70    „      (500.0.) cone, nitric acid (in 1700.0. water).
The phenol, melted in a basin on the water-bath, is slowly
added in small quantities to the nitric acid and water contained
184

PRACTICAL ORGANIC CHEMISTRY

in a large round flask (i litre), and the contents of the flask
well shaken. On the addition of the phenol, the liquid immedi-
ately changes to a deep brown or black colour, and a heavy
dark-br-own oil separates out. When the phenol has been
added, the mixture is allowed to stand for 12 hours. The oil
has by that time collected at the bottom of the vessel, and may
be freed from acid by repeatedly decanting and pouring" in
fresh water (three or four times). The contents of the flask
consist of nearly equal quantities of para- and ortho-nitrophenol
mixed with resinous products. In order to separate the two
isomers, the product is distilled in a current of steam (sec Fitf.
68, p. 107) until the distillate is almost colourless. The ortho-
compound distils in the form of a yellow oil, which may solidify
in the condenser, in which event the water is temporarily run
out of the condenser. The solid in the receiver is separated by
filtration and dissolved in spirit at 40°, to which water is then
added, drop by drop, until a turbidity is produced. Yield, i 5
grams. The solid residue contains the para-compound mixed
with black, resinous substances, from which it is separated by
repeatedly extracting with boiling water. The united portions
of the aqueous extract are boiled with animal charcoal for
half an hour in a large basin, and filtered through a fluted filler
moistened with water. The filtrate is made alkaline with
caustic soda solution, and concentrated to a small bulk (roo
c.c.). If tarry matter separates, it must be filtered through a wet
filter. To obtain the free para-compound, the concentrated
aqueous solution of the sodium salt is cooled, and the separated
sodium salt filtered. The crystals arc dissolved and acidified
with concentrated hydrochloric acid, and the nitrophenol, whirh
separates, is filtered and recrystallised from hot water. Yield,
lo grams.

Properties,—Q-NUrophcnol, sulphur-yellow needles, pos-
sessing a peculiar smell ; m. p. 45°; b. p. 214" ; clistillable with
steam ; soluble in alcohol, ether, and hot water ; less soluble in
cold water.
•^-Nitrophenol, colourless needles ; m. p. 114° ; easily soluble
in alcohol and hot water ; slightly soluble in cold water. See
Appendixi p. 295.
PICRIC ACID                                  Ig

PREPARATION   80.

Picric Acid (Trinitrophenol), C0H9(OH)^No!   4                              1 '

XN02    6

Woulfe, 1771 ; Schmidt, Glutz, Bcr^ 1869, 2, 52.                                    * I

* I
25 grms. phenol.                                                                                           l|^

25     „     cone, sulphuric acid.                                                                       \'fl

i QQ     „     (70 c.c.) cone, nitric acid, sp. gr. 1*4.                     -                          j*

25     „     (20 c.c.) fuming nitric acid, sp. gr. 1-5.                                            |'

tf<)

The  phenol  and  concentrated   sulphuric  acid  are  heated                       ,<' i

together in  a ])orcclain basin for a few minutes, until a clear                       V*

solution   of phenol   sulphonic acid is obtained.     It  is diluted.                        '*

with half its volume  of water,   well   cooled, and  then slowly                        4

added, in small quantities at a time, from a tap-funnel, to the                       ^

nitric acid  contained  in  a  flask  (r   litre), and  well shaken.*-                       \f

The liquid assumes a, deep red colour, a considerable rise of                      If

temperature occurs, and red fumes  are   evolved.     When the                       -f*

phenol sulphonic acid has been added, the flask is placed on.                       *d

the water-bath and heated, with the addition of 25 grams fuming-

nitric acid, for i.....2 hours.*    On cooling, picric acid separates

out as a yellow, crystalline mass. It is diluted with water,
filtered at the pump, and washed free from the mother liquor
with cold water. It is then purified by recrystallisation from a
large quantity of hot water acidified with a few drops of
sulphuric acid. Yield, about 30 grains.

CJ l,(011) +1 F,SO., - C0H4(0H).S03H + H20.

C(;Ha(OH)(NOa)3 + 3H20 + H2SO4.                       if
ft
Properties.-—Yellow, prismatic crystals; m. p.   122*5°;   sub-                       ^i
limes on gently heating ; explodes on detonation ; easily soluble
\\\ alcohol and ether ; with difficulty in cold, more readily in                       f|
hot water ; the solution has a bitter taste.
Reactions.— r. To an aqueous solution of picric acid add a
little potassium cyanide solution, and warm. A brown crystal-
line precipitate of isopurpuric acid separates.
2. Add picric acid and a few drops of caustic socla to a dilute
solution of grape sugar, and warm. The liquid turns deep brown.
186               PRACTICAL ORGANIC CHEMISTRY

3. Dissolve naphthalene in a little spirit, and add an
equal quantity of a solution of picric acid in spirit. Or*
cooling, yellow needles of naphthalene picrate separate,
C10Hg.CcH2OH(NO2)3. Benzene forms colourless crystals,
anthracene, scarlet needles, having a similar composition. See
Appendix, p. 295.

PREPARATION 81.

Phenolphthalein,

V

Baeyer, Ber., 1876, 9, 1230, and Annalen, 1880, 202, 68,
10 grms. phthalic anhydride.
20     „     phenol.
8     „     cone, sulphuric acid.
The phthalic anhydride, phenol, and concentrated sulphuric
acid are heated together to 115—120° in the oil-bath 8—9 hours.
The mass becomes semi-fluid and of a dark red colour. It is
poured, whilst hot, into a basin of water (500 c.c.) and boiled.
until the smell of phenol has disappeared, the water being"
renewed as it evaporates. The undissolved yellow granular
precipitate, on cooling, is separated from the liquid by filtration,
and washed with water. It is then dissolved in dilute caustic
soda solution, filtered from the undissolved residue, and tlie
filtrate acidified with acetic acid and a few drops of hydro-
chloric acid. The phthalein separates out, after standing for
some hours, as a light yellow, sandy powder, which is filtered
and dried. It is purified by dissolving in absolute alcohol witli
the addition of animal charcoal (i part phenolphthalein, 6 parts
alcohol, and \ part charcoal) and boiling the solution on ttoe
water-bath for an hour. The mass is filtered hot, washed witli
2 parts boiling alcohol, and the filtrate evaporated down to
two-thirds its bulk on the water-bath. On adding 8 times trie
quantity of cold water to the cooled solution, the latter becomes
turbid. The liquid is well stirred, and, after standing a few
seconds, filtered through cloth from the resinous oil whicli
separates. On heating the filtrate on the water-bath to expel
FIYUORKSCKIN AND EOSIN

187

excess of alcohol, phenolphthalcin crystallises out in the form
of a white powder.    Yield, 5 grams.

/C(\                 C(C(iH,OH),

Properties.—White, granular, crystalline powder; m. p.
250 253° ; very slightly soluble in water, readily soluble in hot
alcohol ; soluble in alkalis with a crimson colour. See Appendix^
p. 296.

PREPARATION 82.
Fluorescein and Bosin,
xC(iIU)H                           X;,;IlBr/)H

C

c(;H,,a).o

Baeyer, Antmlen^ 1^76, 183, 3.

10 gnus, phthalie anhydride.
15    „      re.sorcinol.
7    „      zinc chloride (fused and powdered).

The phthalie anhydrkle and rcsorcinol are ground together
and heated in a deep tin dish or cylinder to 180". To the
fused mass the zinc chloride is added with continual stirring in
the course of ten minutes. The temperature is now raised to
210" and the heating continued until the mass is quite hard
(about 2 hours). On cooling, the melt is chipped out, pulverised,
and boiled for ten minutes with 150 c.c. water and 10 c.c. cone,
hydrochloric acid. The fluoresccin is filtered off, washed, and
boiled with a small quantity of absolute alcohol to dissolve
impurities. The residue is then dried on the water-bath. Yield
20 grams.

Eosin. — Fifteen grams of the fluorescein are mixed in a flask
with 80 c.c. spirit and ir c.c. bromine are dropped in from a
burette in the course of quarter of an hour. Heat is developed
and the fluorescein gradually dissolves until, when half the
bromine has been added, a clear solution is obtained. Further
addition of bromine precipitates the tetrabromo-compound

I
iSS

PRACTICAL ORGANIC CHEMISTRY

(eosin). After standing two hours the precipitate is filtered,
washed with spirit, and dried at 110° to expel alcohol of crystalli-
sation. Yield 30 grams. .

In order to obtain the sodium compound, 6 grams of the
product are ground in a mortar with i gram of sodium carbonate,
placed in a beaker, and moistened with alcohol. Five c.c. of
water are added and the mixture boiled until the evolution of
carbon dioxide ceases. To the sodium salt 25 c.c. spirit are
added and the mixture boiled and filtered. On standing for
a day or two, the sodium salt crystallises in brown needles.

/OH

co

2C6H4(OH)2 —> C6H4/

I
O

\CO

OH



QHBr

/

OH

C6H



asOII + SBr-->QH,

/|\CflHBr!

I

X

OII

See Appendix^ p. 296.

PREPARATION 8-3.
Salicylaldehyde (0-Hydroxybenzaldehyde)
p-Hydroxybenzaldehyde,
Reimer, Tiemann, Ber.> 1876, 9, 824.          /
r H /OH       ii
^e^^co.H    2    4-
50 grms. phenol.
100    „     caustic soda.
160     „      water.
75     „      chloroform.
The phenol, caustic soda and water are mixed together in £t
round flask (i litre) attached to an upright condenser aricl
heated to 50—60°. The chloroform is then added gradually
SALICYLALDEHYDE                           189

through the top of the condenser and, after each addition, the
flask is well shaken. A gentle reaction sets in, and the temper-
ature rises. At the same lime the surface of the brownish
yellow solution takes a violet tint, which rapidly fades, the
liquid finally assuming1 a deep red colour. When all the chloro-
form has been added, the contents of the flask are boiled for half
an hour. A yellow semi-solid mass separates out of the solution.
The imattackcd chloroform is now distilled off on the water-
bath, the liquid diluted with water and strongly acidified with
dilute hydrochloric or sulphuric acid. A thick red oil separates
out on the surface and is subjected to distillation in steam. An
oil, having a faintly yellow colour, distils over with the water, and-
settles to the botlprn'o'f the receiver. When drops of oil cease
to condense, the distillation is stopped. The distillate, which con-
tains salicylaldchyde and phenol, is extracted with ether, and the
ethereal solution well shaken with a saturated solution of sodium
bisulphite (see Reaction 2, *p. 67). The bisulphite compound
of salicylaldchyde separates out in colourless needles, which are
filtered, washed free from traces of phenol with alcohol and then
decomposed by heating with dilute sulphuric acid. The aldehyde
which separates is taken up with ether, dehydrated over calcium
chloride, the ether driven off and the aldehyde distilled.
Yield, 10 grams. In the distilling flask from which the saliryl-
aldehyde has in the first instance been removed with steam,
there remains a brownish liquid and a dark red substance, which
sinks to the bottom of the vessel, and forms a brittle resin on
cooling. The aqueous portion is filtered hot through a moistened
filter, which retains the resin, and the filtrate, containing /;-hydr-
oxybenzaldehydc, is extracted when cold with ether. On distilling
off the solvent, the aldehyde remains in the form of a yellow
mass of stellar-shaped needles, which may be purified by
crystallisation from hot water. Yield, about 2 grams.

CMClfl - Co

. Colourless fragrant oil, b. p.
196*5^; sp.gr. i '173 at 13*5°; solidifies at 20", forming large
crystals. . Volatile in sttia-m ; soluble in water ; miscible in all
proportions with alcohol and ether.
190               PRACTICAL ORGANIC CHEMISTRY

Reaction.—Add a drop of ferric chloride to the aqueous
solution of the aldehyde. A deep violet colouration is produced

f-Hydroxybensaldehyde.--Cc>\QUTL\tss needles, m. p. 115—116°;
scarcely soluble in cold water, readily in hot water, alcohol and
ether. Non-volatile in steam. The bisulphite of sodium
compound dissolves readily in water.

Reaction.—The same as above ; but the colouration is .less
intense. See Appendix, p. 297.

PREPARATION 84.
Salicylic Acid (0-Hydroxybenzoic Acid), QH4\co OH
Kolbe, / prakt. Chem., 1874, (2), 10, 95.
10 grms. caustic soda.
23     „     phenol.
This preparation should be commenced first thing in tlie
morning. Dissolve the caustic soda in about 10 c.c. of water In
a small porcelain basin and add the phenol. Heat the basin on
wire-gauze over a very small flarne, and, whilst holding it firmly
with a small clamp (tongs are too insecure), keep constantly
stirring with a glass rod. After a short time the mass becomes
stiff and balls together. The basin should now be removed
from the gauze, and the mass stirred and broken up as it cools.
When still warm, it is sufficiently hard to powder in a mortar.
It is quickly powdered and transferred to a small retort (200 c.c.)
heated in an oil or paraffin bath to 130—140°, and dried toy
passing over it a fairly rapid current of dry hydrogen from n.
Kipp. In about an hour all the moisture is removed, and trie
body of the retort appears dry. The light coloured mass in the
retort is allowed to cool whilst the hydrogen is passing throug'li,
then broken up and shaken into a mortar, when it is quickly
powdered and replaced. The object of the above operation is
to obtain perfectly dry, unchanged and well-powdered, sodiu.ni
phenate, upon which the success of the preparation entirely
depends. A moderate stream of carbon dioxide, dried throug'li
concentrated sulphuric acid, is now passed over the surface of
SALICYLIC ACID                            191

the sodiLiiT-^ phericite by means of a bent tube fixed through the
tubulus of t*10 retort» anc^ terminating just above the substance.
The tem~pGrnt"uie °* ^1C 01^"^at-n 's gradually raised from 140° to
180__loo0?    whilst fresh surfaces  are  exposed  by  occasionally
stirrinc*- vv/itl* a glass rod inserted for a moment through the
tubulus A-t the end of four hours the temperature is raised to 190
—200° foir zxtiother hour, and the process stopped. During the
heatinc^- %\. considerable quantity of phenol distils, and solidifies in
the iiecrlc of l-nc retort, whilst the contents become dark coloured.
The rn^iss is shaken out into a basin without disturbing the phenol
in the necl£> anc^ the residue dissolved by filling the retort two-
thirds full of water. This is poured into the basin containing
the otHcii" portion, which soon dissolves. The solution is acidi-
fied wit In concentrated hydrochloric acid, which throws down
impure sn.lic.:ylic acid in the form of a dark brown pre-
cipitate. "When cold, the precipitate is filtered at the pump,
and w;Exsl"i<:i<^ with a little cold water. A further quantity
may foo ol:>t*lined by evaporating the filtrate to a small bulk. It
is purified l->y dissolving in water, boiling with a little animal
charcon.1 n.iicl filtering. The filtrate deposits the acid, on cooling,
in colov.irle.ss needles. Yield about 6 grams.
J.    C0T~Ir>0 Na + CO, = C(!II,O.CO.ONa
Sodium phenyl ourboniUi!.
2. CeI-I0O.CO.ONa
I )isodiuin siilicylulc.
Projf*£??*-/****?*- Colourless needles; in. p. 155—156''; soluble in
ilcohoi n.incl hot water, rex)1 parts water dissolve 0*225 part at
15° ancl 7~<J^5 parts at 100".
Iteu£'jft&?zs'. r. Dissolve a little of the acid in water and add
a drop of" f<e rric chloride. A violet colouration is obtained.
2. Gi"in.cl v.ip some of the acid with soda-lime and cover with a
shallow In.yor of the same substance. On heating strongly the
smell of* pliciiiol is perceived.
C0I-I.,<OH)CO.OH + CaO = C6HflOH + CaCO;J.
See ^4.jp2&*??uiiX) p. 297.
192               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 85.
Quinone and Qninol (Hydroquinone),

C H ^° and C H /OH 1
C6w4-        ancl ^^H

Woskresensky, Annalen^ 1838, 27, 268 ; Nietzki, Ber., 1886,
19, 1467 ; Meyer and Jacobson, Lehrbuch, vol. ii., 421.
25 grms. aniline.
200   „      (no c.c.) cone, sulphuric acid.
750 c.c. water.
80 grms. potassium bichromate.1
The water and aniline are mixed together in a large glass jar
(i^- litres) and the sulphuric acid added. The mixture is cooled
in ice and stirred with a turbine (see Fig. 64, p. 91). The finely-
powdered bichromate is added every few minutes in small quan-
tities on the end of a small spatula, until about one-third has
been added, care being taken that the temperature does not
exceed 10°. The mixture is then left to stand over night, and
the remaining two-thirds of the bichromate introduced as before.
Aniline black separates out in the first part of the operation,
and in the second part of the process gradually dissolves,
giving a deep brown solution. The liquid, after standing for
four to five hours more, is divided into two about equal portions.
One half is shaken up, not too vigorously, with a large quantity
(200 c.c.) of ether three times. The same ether may be distilled
and used again. Vigorous shaking produces an emulsion, which
very slowly separates. On distilling off the ether, the quinone
remains in the form of yellow needle-shaped crystals, which may
be purified by sublimation. The substance is placed in a flask
attached to a condenser, and a rapid current of steam blown
through. The quinone sublimes and collects in the receiver,
and is separated from the water by filtration, and dried. Yield
about 10 grams.
1 Or an equivalent quantity of sodium bichromate (75 grams), which may be
dissolved in 3 — 4 times its weight of water and delivered from a tap-funnej
QUINONK AND OUINOL

The reliction consists in the oxidation and elimination of the amino-
<_n'oup and simultaneous replacement <>f l\vo hydrogen a'tnms in the
hen/ene nucleus hy oxygen, and cannot well he expressed in the
form of equation.

Pro/tM'fies. ~~( .ioklen-vellow, noodle-shaped crystals ; m. p.
Ii6: ; with difficulty soluble in water, readily soluble in alcohol
and ether ; sublimes on heating ; its vapour has a penetrating-
sin ell and attacks the eyes.

Kctii'tioii. ....... Dissolve a few crystals in water and add a solution

of sulphur dioxide. The solution first darkens from the forma-
tion of quinhydrone, C,.I IVO.,. C,.I i. t(()Il ).,, and then becomes
colourless and contains quinol.

Qtlinol. ...... The other half of the product  is treated with a

current of sulphur dioxide until, after standing for a time, it
retains the smell of the gas.* The sulphur dioxide is most
conveniently obtained from a bottle of liquid, or it may be pre-
pared by dropping1 concentrated sulphuric acid from a tap-
funnel on to sodium sulphite. The liquid, after standing one to
two hours, is extracted with ether until no more quinol is
removed. The ether is distilled off, ami the dark coloured
residue rccrystallised from water with the addition of sulphur
dioxide and a little animal charcoal. Yield about 10 grains.

c,;n.,o2 4- sex 4- 2iLo - c.jii.jf

/V<yVr//V,v.~- -Colourless prisms ; m.p. 169' ; sublimes at a
gentle heat ; easily soluble in alcohol, ether, and hot water.

Rent'ti'tws. — i. To a solution of quinol in water, add a few
drops of ferric chloride. The solution turns brown and ether
now extracts quinone.

Ct;H4(On)., 4- 2FeCl;{ - CUH,,(), + 2FeCl, 4- 2HC1.

2. Add to the solution of quinol in water, a drop of copper
sulphate, and caustic soda, and warm. Cuprous oxide is pre-
cipitated.

cfln4(Qii)a 4- 2Cuo = tyi.tO., + Gu-jU + H.A

See Appendix^ p. 297.

ft'lf

COHEN'S ADV. i». o. c.
194

PRACTICAL ORGANIC CHEMISTRY

PREPARATION 86.

Benzyl Chloride, C0H5CH2C1

Cannizzaro, Annalen, 1853, 88, 129.

100 grms. toluene.

i     „      phosphorous trichloride.

The apparatus consists of vessels for evolving and drying chlo-
rine (see Fig. 62, p. 88) and a weighed retort (300 c.c.) standing"
on wire-gauze, into which the toluene is brought. (Fig. 80.)
chlorine enters through an inlet tube, fixed through the t
of the retort, the neck being fixed to a reflux condenser.

FIG. 80.

dry chlorine is conducted into the toluene, which is kept boiling:
gently until it has gained about 37 grams in weight.* The liquid.
turns yellow, and hydrochloric acid fumes are evolved sit tlie
upper end of the condenser. When the reaction is complete tlie
contents of the retort are distilled.* At first unchanged toluene
distils ; the fraction boiling at 165—185° contains nearly *tlie
whole of the benzyl chloride, and forms the greater pa,rt of
the product. The liquid, which passes over above 185°, is a
mixture of higher chlorinated compounds, and consists cl~k.iefly
of benzal chloride, C6H5CHC12, and benzotrichloride, C6F
15KNXYL ALCOHOL                              195

tainintf the ben/.yl chloride is repeatedly frac-
t-ollitted Linlil 21 liquid is obtained, boiling at 176 ~i8o°, wl.ich
is nearly pure l.XMi/yl chloride. Meld 80 90 grains.

C'ti M r^ H3 + Cl, - C,;I IAC1 -LCI -I- HC1.

f*ropcrtii?s* ------ Oolourless liquid with an irritating- smell ; b. p.

176° ; sp. gT.   I "107 at 14".    See Appendix, p. 299.

1* UK PA RATION   87.

"B enzyl Alcohol, c:,j 1 1 ,C 1 1 ,0 11
-l )aum, Widmau, /A1;*., 1892, 25, 3290.

20 yrrnis%   lji.*n/yl I'hloride.
16       ,,          j>olassiuiu (,:arl)on;Ue (in 200 c.c. water).
In a round llask (i litiv) attached to a reflux condenser,
the mixtiiro of ben/yl chloride and jxitassiuni (sarl)onate
solution over \vi re-^auzc: with the addition of a few bits of porous
pot. The l3<>Slin^ must be continued until the smell of benzyl
chloride hrts <1 inrt ppeared (6-— 8 hours). Extract the liquid with
etlner, clehyclrsito over potassium carbonate, decant through a
filter and clistil off the ether on the water-bath. Continue the
distillation, ovor \virc-^au/.c, run the water out of the condenser
and collect a.t ^200 -2 id3. Yield 12 ...... 15 grains.
2CGH6CMoCl   -4-   I I/') -f-.K,<;0;l -• 2C()flr,Cl I,OI I + 2KC1 + C02.
properties.. -—-Colourless Jiquid with a faint aromatic smell;
ID. p. 206-5° ; SI>- l^1"- 1*05 at 15*4° ; moderately soluble in water.
JRe&ctiorzs* — - J . Boil 2 or 3 drops with 2— 3 c.c. dilute nitric
acicl ( I H N O:i74. T I ./J) ; Ijcnxaklehydc is first formed and is detected
by the smell. On continued boiling, benzoic acid is formed and
separates on. oooling in crystals.                                      •
-2. Warm 1 o.t*. of the alcohol with i c.c. concentrated hydro-
clilorlc acicL 'J'he clear solution becomes turbid and benzyl
clilorkle scpz.ii*:ites out.
C(;I I,,C: ILOM + MCI « C0H6CH.,Cl + HSO
Sec Ajf>f>c/'itf/~\:) p. 300,
PRACTICAL ORGANIC CHEMISTRY

PREPARATION 88.
Benzaldehyde (Bitter Almond Oil), C0H;VCO.H
Liebig, Wohler, Anna/en, 1837, 22, i ; Lauth, Grimaux, A?m-
vlen, 1867, 143, 186.
50 grms. benzyl chloride.
40     „     copper nitrate.
500   c.c.   water.
The mixture of benzyl chloride, copper nitrate and water is
heated to boiling in a round flask (i\ litre) with upright
condenser on the sand-bath for a day (8—9 hours). A slow
current of carbon dioxide is at the same time passed through
the liquid to prevent oxidation of the benzaldehyde by absorp-
tion of oxygen from the air. During the process nitrous fumes
are slowly evolved. When the reaction is complete, the contents
of the flask are extracted with ether, and the yellow oil remaining,
after distilling off the ether, is well shaken with a satu-
rated solution of sodium bisulphite1 and allowed to stand for
a time. The colourless crystalline mass which separates
out is filtered, washed with a little alcohol and ether, and then
drained on a porcelain filter. The aldehyde is regained by
adding dilute sulphuric acid in excess and distilling in steam.
The distillate is extracted with ether, dehydrated over calcium
chloride, decanted, and the ether distilled off. Yield, about 15
grams.
2CCH3CH2C1 + Cu(NO3)2 = 2C0H6COH + CuCl2 + 2HNO,.
Properties,—Colourless liquid, with a pleasant smell ; b. p.
179° ; sp. gr. ro5o4 at 15°; it quickly oxidises in the air, forming
benzoic acid.'
Reactions,—i. Leave a drop of benzaldehyde on a watch-
glass. It solidifies by becoming oxidised to benzoic acid.
2. Add 5 c.c. concentrated ammonia to I c.c. benzaldehyclej
cork up and leave two days. Crystals of hydrobenzamide,
1 The solution is prepared either by dissolving solid sodium bisulphide in water or
by passing sulphur dioxide into powdered sodium carbonate covered with a shallow
layer of water. The carbonate dissolves with effervescence, forming a heavy apple*
green liquid smelling strongly of sulphur dioxide
a- AND 0-BENZALDOXIMES                       197

(Cc*^^       ':I    2>    separate out, which may be recrystallised from
spiri^              s« y

*C,.Lv---------.2NH3 = (CGH5CH),N2+3H20.

J-t ont Qrx tjie Water-bath 2 c.c. benzaldehyde and 2 c.c.
to i ex^ hour. Crystals of benzalaniline are formed
iig-5 C(iHL3COH + C0H5NH2 = C0HSCH:N.C0H3 -f H2O,
mo.y bci filtered and crystallised from spirit ; m. p. 42°.
*t*cc llp> together 10 grams of benzaldehyde with 9 grams
x3OtilsH in 6 c.c. of water until a permanent emulsion is
z\.nd lGt stand 3—4 hours. Dissolve the solid product in
a littlo xviitof and shake out with ether twice. On acidifying
the a.cj[i.ioou.s -portion with hydrochloric acid, benzoic acid is
precipit-rxtecl. jriiter and wash with a little cold water and dry.
Distil tlic Gtlaer from the ethereal solution. The residue
is benzyl ;UCoi-ol (Cannizzaro).

3C:ttHrtCo H + KOH = C6H6COOK + CflH3CH2OH.
ctlso Ueactions on p. 135 and p.1 174, and Appendix ^ p. 300.

PREPARATION 89.

«- and-0-Benzaldoximes, C0H6CH:NOH
Beckmann, Ber.9 1890, 23, 1684.

s. benzaldehyde.
1 5     yy        hydroxylamine hydrochlori-de.
*4     yy       caustic soda (in 40 c.c. water).
Tlio ssolution of caustic soda and benzaldehyde are mixed and
the liyclroxylfxrnine hydrochloride gradually added with constant
sha1cii™i|4". Hie liquid becomes slightly warm and the oil even-
tu-aily dissolves, forming a yellow solution which has lost the
smell of toenza-lclehyde. On cooling, a crystalline mass of the
hydrocliloride of benzaldoxime separates. Sufficient water is
added, to form, a clear solution, through which a current of
carbon dioxide is passed. A colourless emulsion of the a- or
#;z//-£xlcloxime separates on the surface and is extracted with
ethei", dehydrated over anhydrous sodium sulphate and the
ether rcMiiovod on the water-bath. Impure benzcz^//aldoxime
remn-iiiH and is purified as follows. It is poured into a
satuiTLtcsd soli_ition of sodium ethoxide in alcohol (prepared by
dissolving 5 |>'i*a,ms sodium in 60 c.c. alcohol), when the aldoxime
PRACTICAL ORGANIC CHEMISTRY



separates as the sodium compound in the form of a semi-solid
mass. It is filtered and washed with a saturated solution of sodium
ethoxide in alcohol to dissolve out the /3-oxime. The product
is dissolved in water, saturated with carbon dioxide and
extracted with ether as before. Dry air is then drawn through
the liquid to remove the last traces of ether when, if pure,
the oxirne, on cooling to o°, solidifies. If not, it should be
distilled in i>acuo. At 12 mm. it boils at 122—124° : at lomm,
at 118—119°.
Yield, 10 grams.
-f- 3HO.,
C6H5.CHO + NH..OH.HC1 -f- zNaOH = C0H5CH:NONa + NaCi
C6HaCH:NONa + CO2 -f ILO = QH5CH:NOH + NaHC03.
Properties   of   a-Benzaldoxime.—Colourless  needles,  m. p.
34—35°-
Reaction.—Dissolve a small quantity of the a-oxime in a few
drops of acetic anhydride, warm if necessary, and cool quickly
by adding a little ice. Add to the clear solution solid sodium
carbonate and a little caustic soda solution. The solution
becomes clear on shaking or warming.
0-Benzaldoxime.—The various steps in the preparation
of the /3-oxime must be carried out continuously, and it is
therefore necessary to- be provided beforehand with about
300 c.c. of pure anhydrous ether.
The a-compound is dissolved in 50 c.c. pure dry ether, and
dry hydrogen chloride is passed in with constant shaking to
prevent the delivery tube from becoming blocked. Colour-
less crystals of the hydrochloride of the /3-oxime separate
and are filtered and washed with dry ether and then placed
in a separating funnel and covered with a layer of ether.
A concentrated solution of sodium carbonate is gradually added
with constant shaking until no further effervescence is observed.
Sodium chloride is precipitated and the /3-oxime dissolves in
the ether. The ether extract is separated, dehydrated over
sodium sulphate, and the ether removed as rapidly as possible
at the ordinary temperature by evaporation in vacua* The
residue crystallises, and when pressed on a porous plate leaves
a mass of small silky needles, m. p. 126—130°. It may be re-
BKNZOIC ACID           ^                      199

_____......._  _                    .....w_.___________.___        .............._______________\__________________V              X       ^"^     £„.

crystallised by dissolving it in the smallest quantity of ether"and
then adding petroleum ether.                ;     •

The yield is theoretical.                       ,     ,;„

IIO.N       "*"           N.on.irci       ^            N.OII

<x- or <f////-oxnne.                                                                                        /3- or ,s^v/-oxime.

Properties of the $-ftcnzaIdoxu)n\—Colourless needles, m. p.
130°.

Reaction,—Repeat the reaction for n-benzaldoxime. In this
case bcnxonitrile is formed, which separates in oily drops having
a characteristic smell. See Appendix^ p. 301.

I* KKl'AR AT/ION  90.
Benzole Acid, C0H6CO.OH
5 gnus. bcn/,yl chloride.
4     ,,     anhydrous sodium carbonate (in 50 c.c. water).
8*5     „     potassium jKirmanganate (in 150 c.c. water).
The benzyl chloride and sodium carbonate solution arc mixed
in a round flask (| litre) attached to a reflux condenser, and
boiled gently over wire-gau/'ie, whilst the permanganate solution
is gradually dropped in from a tap-funnel pushed through the
top of the condenser. In the course of 2 — 3 hours the pink
colour of the permanganate will have vanished and been replaced
by a mass of dark brown precipitate of manganese dioxide.
When the liquid is cold, a stream of sulphur dioxide is passed in
until the manganese dioxide is dissolved (see p. 166). The
liquid is allowed to cool and the benxoic acid, which separates,
is filtered at the pump, washed with a little cold water and
recrystallised from hot water; m. p. 121°. The yield is
theoretical. The reaction probably occurs in two steps.
1.  2C,,Hf)CH.,Ci -f NaXO-j H- II..O -
2C(}Hr)CH,OH -1- 2NaCl + CO3.
2.  3C6H6CH2OI1 f- 4KMn<)4 -
3CnII:,COOK 4- 4MnO2 + KOH + 4H3O,
PRACTICAL ORGANIC CHEMISTRY

Properties.—Crystallises in needles; m. p. 121°; on heating-
it melts and sublimes ; soluble in hot water, alcohol and ether.
It distils in steam.

Reactions.—i. Make a neutral solution of ammonium benzoate
by adding excess of ammonia to benzole acid and boiling until
neutral To different portions add solutions of calcium chloride,
ferric chloride, silver nitrate and lead acetate and note the
results. .

2. Grind up o'5 gram of the acid with four times the weight of
soda-lime and heat gently at first and then more strongly.
Vapours of benzene will be given off, which may be detected by
the smell. CGH5CO.OH + CaO = CGH6 + CaCO3,

See Appendix, p. 302,

PREPARATION 91.
m-Nitro, m-Amino- and m-Hydroxybenzoic Acid,

/NO,      r „ /NH,      r H /OH         i

3

40 grms. benzoic acid. *
..'•"' '                           80     „     potassium nitrate.
TOO   c.c.   cone, sulphuric acid.
The benzoic acid and potassium nitrate are mixed and care-
fully powdered. The sulphuric acid is warmed to 70° and
stirred mechanically, whilst the mixture of benzoic acid and
nitrate is added slowly, so that the temperature does not exceed
80°. When all is added the temperature is raised to 90°, and
kept at this temperature until the nitrated acid separates as an
oily layer on the surface. On cooling, the layer solidifies and
can be separated. It is then distilled in steam to remove
benzoic acid. The residue containing the nitrobenzoic acid is
heated to boiling and made slightly alkaline with baryta. Two
litres of water are added and the liquid raised to the boiling
point by passing in steam and then filtered. On cooling, the
barium salt crystallises and is filtered off and decomposed with
hot dilute hydrochloric acid. The precipitated acid is re-
crystallised from water ; m. p. 141°. Yield, 28 grams,
m-BROMOBENZOIC ACID

in

m-Ainixiobenzoic Acid

20 gnns. nitrobenzoic acid.

40     „      granulated tin.
120   c.c.    cone, hydrochloric acid.

The nilrobenzoic acid, tin, and hydrochloric acid are mixed
„„ a litre flask and wanned until the reaction begins. When
the first vigorous action is over, the mixture is heated on the
water-bath until the tin is dissolved. The liquid is poured
into a basin and evaporated on the water-bath to expel the
excess of hydrochloric acid. The tin is then precipitated by
passing' into the hot, dilute solution a current of hydrogen
sulphide. The sulphide is filtered and washed with hot water,
and the filtrate evaporated to dryncss. To obtain the free acid,
a small portion of the residue is dissolved in very little water
made alkaline with ammonia, and acidified with acetic acid.
It is recrystallised from water, and melts at 174°.

m-Hydroxybenzoic Acid,

15 grms. ;//-;iminobenzoic acid hydrochloride (in 200 c.c. water).
6*5    „     sodium nitrite (in 15 c.c. water).

The nitrite solution is slowly added to the solution of the
hydrochloride dissolved in water. The liquid is heated on
the water-bath until the evolution of nitrogen ceases, and then
filtered and concentrated. The hyclroxybenzoic acid separates
on cooling as a brown mass, which may be purified by dissolving
in water and boiling with animal charcoal. It separates in
colourless crystals, in. p. 200°. Yield, 7 grams, See Appendix,
P- 3°3-

PREPARATION 92.

m-Bromobenzoic Acid,  C(!H/5jL          l

v

Hiibner, Petermann, Anmilen, 1869, 149, 131.
5 grins, benzoic acid.
7     „     bromine.
30 c.c. water.
The mixture is brought into a thick-walled tube, closed at one
end and sealed in the usual way.    The tube is heated in the
202               PRACTICAL ORGANIC CHEMISTRY

tube furnace to 140—150° for eight to nine hours. After cooling,
the capillary is opened and the tube removed from the furnace.
The bromine will have completely disappeared, and colourless
crystals of bromobenzoic acid now fill the tube. The contents
are removed, filtered, and boiled with water (100 c.c.) in a
basin to drive off unchanged benzoic acid. The liquid is
cooled, filtered, and the bromobenzoic acid crystallised from
hot water. Yield, 5 grams.

CGH5CO.OH + Br2 = C6H4Br.CO.OH + HBr.
Properties.—Colourless needles ; m. p. 155°,

PREPARATION 93.
CCH5.CHOH
Benzoin,         |
C0H6.CO
1                            Liebig, Wohler, Annalen, 1832, 3, 276; Zinin, Annalen, 1840,
34, 186.
25 grms. benzaldehyde.
5     „     potassium cyanide (in 20 c.c. water).
50   c.c.   absolute alcohol.
,]                              The mixture of benzaldehyde, potassium cyanide and alcohol
\                           is heated on the water-bath  with an  upright  condenser for
Jl                           about half an hour.    On cooling the liquid, the benzoin separates
1  ,                          out as a mass of small colourless crystals, which are filtered and
'j                           washed with a little alcohol.    Yield, about 20 grams.    A portion
;,:                          of the substance may be purified by recrystallisation from spirit.
|                                              2C6H5COH = C6H5CO.CH(OH).CGH5.
|                             Properties.—Colourless prisms; m. p. 137°;  slightly soluble
*                  -        in water ; soluble in alcohol and ether.
\                             Reaction.—Add Fehling's solution to benzoin dissolved in
,|                          alcohol. Benzil is formed and cuprous oxide precipitated,
•vj                          Benzil is also formed on oxidation with nitric acid.
fa
BENZILIC ACID                                203

Benzil, C0H5CO.CO.C6H6
15 grms. benzoin.                                                                            *
35     „     cone, nitric acid, sp. gr. 1-4.
The benzoin and nitric acid are heated on the water-bath with                       '    ,
an air condenser, the flask being occasionally shaken. Nitrous
fumes arc evolved, and the crystals of benzoin are converted
into a yellow oil, which, after two hours' heating, is free from un-
changed benzoin. The contents of the flask are now poured
into water, and the yellow crystalline deposit separated by
filtration, washed with water, and recrystallised from alcohol.
Yield, 10—12 grams.
Properties.— Yellow prisms;  m. p. 95°; insoluble in water;                         '«
soluble in hot alcohol.                                                                                           * \>
Reaction.—i. Dissolve a smalt quantity of benzil in a little
alcohol, acid a fragment of caustic potash and boil. A violet
solution is obtained.                                                                                             , '
Benzilic Acid, (C6H5)2C(OH).CO2H                                      '   ,
10 grms. benzil.                                                              4
50     „     caustic potash.
The caustic potash is melted with a small quantity of water in a                      ,
silver or nickel crucible. The temperature of the mass is brought                     ;M
to 150°, and the finely powdered benzil added.   The benzil melts,                     '•'
and the mixture shortly changes to a solid mass of potassium                       ffj
benzilate.     The  cooled  melt  is   dissolved  in water, and the                       jg
alkaline solution acidified with hydrochloric acid, which precipi-                     fiti
tates the bcnzilic acid.    The crystalline mass, which contains          .              '^'
small quantities of benzoic acid, is separated from the mother-                         t(l^
liquor and washed with cold water.    It is then transferred to a                         *.,^
porcelain basin, dissolved in hot water, and the solution boiled                         n >,'
until the smell of benzoic acid has gone.    On cooling, benzilic                         ^
acid crystallises out, and is purified by a second crystallisation                          l|
from hot water.                                                                                                               )<.>'
C«Hfi.CO.CO.CflHfi+ KOH =(C0H5)aC.(OH).COOK.                                    !|
/^-^;'//^.—Colourless needles ; m. p. 150° ; scarcely soluble                         |§
in cold, readily in hot water and alcohol.                                                                  ||*
Reaction.—Add a little concentrated sulphuric acid to benzilic                         i||
acid.    It dissolves with an intense red colour.    See Appendix^                         M
P- 3°3-                                                                                                       U
204               PRACTICAL ORGANIC CHEMISTRY

PREPARATION  94.

Cinnamic Acid (Phenylacrylic Acid),
C0H6.CH:CH.C02H

Bertaq-nt-ni, Animlcn, 1856, 100, 126; Perkin, Trans. Chcm.
Soi;, 1868, 21, 53 ; Fittig, Ber., i8Si,14, 1826.

20 grms. benzaldehyde.

10    „     sodium acetate (fused).

30  . „     acetic anhydride.

The mixture of benzaldehyde, sodium acetate, and acetic an-
hydride is heated to 180° in a small round flask with upright
condenser in an oil-bath for about eight hours. The mass is
poured out whilst hot into a large round flask (i. litre), sodium
carbonate added until alkaline, and any unchanged benzaldehyde
distilled off with steam. After filtering from tindissolved resin-
ous by-products, hydrochloric acid is added, which precipitates
the free cinnamic acid in white crystalline flakes. It may
be purified by recrystallisation from hot water. Yield, 15 — 20
grams.

C0Hs.CH:CH.CO.ONa+H9

Properties.— Colourless prisms ;  m. p. 133° ; b. p. 300 — 304°-
See Appendix, p. 304
PREPARATION 95.
Hydrocinnamic Acid (Phenylpropionic Acid),
C0H6CHa.CH2.COaH
Erlenmeyer, Alexejeff,   Annalcn,  1862, 121,  375, and  1866,
137,237-
10 grms. cinnamic acid.
100     „     water.
170     „     sodium amalgam (2-J per cent).
The sodium amalgam is prepared by warming 200 grams  of
mercury in a porcelain basin for a few minutes.    The mercury
MANDKLIC ACID                              205

is poured out into a mortar which is placed in the fume cup-
board, the window ot which is drawn down so as to protect the
face, rive grams of sodium are introduced in small pieces, the
size of a pea, and pressed with a pestle under the surface of the
mercury. Kach piece dissolves with a bright flash. The
amalgam is poured out whilst semi-fluid on to an iron tray,
broken up, and kept in a wide-necked stoppered bottle.1

The cinnamic acid and water are introduced into a strong
beaker or bottle (300 c.c.), and the liquid made slightly alkaline
with caustic soda, which dissolves the acid forming the sodium
salt. The sodium amalgam is added in small pieces from time
to time and the liquid thoroughly agitated. The solution, which
remains clear, becomes slightly warm, and the amalgam soon
liquefies, but no hydrogen is evolved until towards the end of
the operation. When the whole of the amalgam has been
added, and bubbles of gas cease to be given off, the solution is
decanted from the mercury, which is rinsed with water. On
acidifying the solution with hydrochloric acid, hydrocinnamic
acid is precipitated as a colourless oil, which solidifies on stand-
ing. It maybe recrystalliscd from a large quantity of warm
water. Yield, 8—-9 grams.

7V^/vr//V.v.—• Long colourless needles; m. p. 47° ; b. p. 280°;
soluble in water and alcohol ; volatile in steam. See Appendix^
p. 306.
l^W-
PRKP A RATION   96,                                                           jfl
Mandelic Acid, C0Mfl.CH(OH).COOH                                   ||
iifjfe:'.!
Friedliinder,  Thccrfarbcnfabrikation IV,  160.                                   fit ;-
15 grins, benxaklehyde.                                                                         |- \
50 c.c. cone, sodium bisulphite solution.                                                if \
12 grms. potassium cyanide (in 20 c.c. water).                                       if p
The benxaklehyde and sodium bisulphite are mixed together                      I j
and stirred.     The  mixture  forms  a  semi-solid  mass  of the                      1 \
1 If larger quantities uf amalgam are required, the mercury is heated in a small                            if f
enamelled pan, or crucible, the sodium added, in one lot, and the vessel immediately
closed with a ltd, which is held down with long crucible tongs until the reaction is
over, and then poured out whilst fluid.
206               PRACTICAL ORGANIC CHEMISTRY

bisulphite compound, which after standing for half an hour is
filtered and pressed at the pump and washed with a little water
and spirit. The mass is then ground to a thick paste with water
and true solution of potassium cyanide added. After a short
time mandelic nitrile separates as a reddish oil and is removed
by means of a tap-funnel with the addition of a lit'tle ether.

The ether is allowed to evaporate on the water-bath and th e
nitrile is then hydrolysed by continuing to heat it on the water-
bath with the addition of 4 — 5 times its volume of cone.
hydrochloric acid until crystals appear on the surface. Water
is added and the hot liquid decanted and filtered from any oil.
On cooling, the crystals are filtered, washed with a little cold
water and dried. A further quantity can be extracted from the
filtrate with ether. It may be recrystallised from benzene,
Yield, 10 — 15 grms.
C0H6CH(OH)CN + HCl + 2HoO
= C0H6CH(OH).COOH + NH4C1.
Properties. — Colourless needles, m. p. 118-119°; dissolves
readily in hot water and in 6 parts of water at 20°. The acid is
racemic; the active components exhibit a rotation of [a]fju= ±:
157° in aqueous solution. See Appendix^ p. 306.
PREPARATION 97.
Phenyl Methyl Carbinol, CGH5 CH(OH).CH3
Grignard, Compt. rend. 1900,  130, 1322 ;   Klages and   Ullen-
dorf, Der., 1898, 31, 1003.
36 grms. methyl iodide.
150 c.c. ether (purified and carefully dried over sodium).
6 grms. magnesium ribbon or powder.
26    „   benzaldehyde.
The magnesium methyl iodide is first prepared and Is
formed by the action of methyl iodide on the metal. The
magnesium ribbon or powder is placed in a dry, round fin sic
PllKNYL METHYL CARBINOL

207

(i litre), connected with a long- condenser and dropping funnel
as shown in l<'ig. Si.

'Hie methyl iodide and 50 c.c. of dry ether are mixed in a
separate vessel and 20 c.c.
of this mixture poured on
to the magnesium. In a few
seconds a vigorous action
usually sets in or if it is de-
layed may be started by
adding a crystal of iodine.
When the first reaction has
subsided, 70 c.c. of dry ether
are added, and the remainder
of the alkyl iodide and ether
mixture run in drop by drop
from the tap-funnel. The
contents of the Mask arc
then boiled on the water-bath for half an hour when (if there
has been no loss of alkyl iodide) the magnesium completely dis-
solves.

Fic.  8r

The flask is now disconnected and whilst it is kept cool in ice-
water the ben/aldehyde mixed with an equal volume of dry ether
is dropped in from a tap-funnel with constant shaking. The
white solid magnesium compound separates and is left over-
night. ^

The contents of the flask are cooled under the tap whilst water
and just sufficient hydrochloric acid to dissolve the magnesia
are added, the acid being cautiously dropped in from a tap-
funnel. The aqueous layer is removed in a separating funnel
and the ether washed first with sodium bicarbonate solution,
then with sodium bisulphite (to remove free iodine) and again
with sodium bicarbonate.

1
208               PRACTICAL ORGANIC CHEMISTRY

The ether extract is then dried over potassium carbonate and
the ether removed by distillation on the water-bath. The
phenyl methyl carbinol which remains is distilled under reduced
pressure; b. p. 100° at 15 mm. ; IIO~IIIQ at 28 mm. ; 118° at
40 mm. Yield, 20 grams.

The same method may be used without modification for pre-
paring phenyl ethyl carbinol using a corresponding quantity of
ethyl iodide. See Appendix^ p. 307.

PREPARATION 98.
Benzoyl Chloride, C0H5CO.C1

Wohler, AnnaJen, 1832, 3, 262 ; Cahours, Annalcn, 1846, 60,
255.

28 grms. benzoic acid.

50   „     phosphorous pentachloride.

A round flask (250 c.c.) is fitted with an air-condenser. The
phosphorous pentachloride is introduced from the bottle and
weighed by difference. The operation must be conducted in
the fume-cupboard. The benzoic acid is then added, and the
air-condenser attached to the flask.* The action begins almost
immediately, and clouds of hydrochloric fumes are evolved.
The whole contents become liquid and consist of benzoyl
chloride (b. p. 200°), phosphorous oxychloride (b. p. 107°), and
unchanged pentachloride. Most of the oxychloride may be
removed by distilling in vacua on the water-bath. The re-
mainder is fractionated at the ordinary pressure and collected at
190-200°. Yield, 20 —25 grams.

Properties. — Colourless liquid, which fumes in the air and
possesses a pungent smell ; b. p. 198*5° ; sp. gr. 1*214 at 19°.

Reactions. — i. Add a few drops of benzoyl chloride to i c.c. of
water ; the benzoyl chloride does not decompose at once, and
requires warming for some time before it is completely dissolved
(compare acetyl chloride, p. 74).

2. Add 2 c.c. ethyl alcohol to i c.c. benzoyl chloride and
caustic soda solution until alkaline, and warm gently. After a
time the smell of benzoyl chloride disappears, and ethyl benzoate

• i
1
KTI1VL BKNZOATE                              209

remains as an oily liquid with a fragrant smell. C(5H5COCl-f
CoHftOm- NaOll -•••Clil-lfl(:0()C,il.4-NaCl + H:iO. Repeat the
same reaction with phenol and separate the solid phenyl
ben/oat e. (Schotten-Baumann reaction.)

3. Add 5 grams benzoyl chloride to 10 grams ammonium
carbonate in a mortar* and grind up well. The reaction pro-
ceeds quietly. If after ten minutes the smell of benzoyl chloride
still remains, add a few drops of concentrated ammonia. Add
cold water and filter. Bcnxamide remains on the filter in the
form of a white crystalline powder, and maybe recrystallised
from hot water; m. p. 128'''. C(;Ilr>COCl + 2NH4HCO.} =
CCHSCON 1 1,-f N I I.tU + 2CO, + 2l!,0. See Appendix, p. 308.

PKKPAKATION   99.
Ethyl Benzoate (Ethyl  Benzoic Ester), CGH-CO.OC2H5
K. Fischer and Speier, /?<.r., 1895, 28, 1150
25 grms. benzoic acid.
75    >i      (90 c.c.) absolute alcohol.
Pass dry hydrochloric acid gas (seep. 93) through the alcohol,
cooled in water until it has increased about 3 grams in weight.
Add the benzoic acid and boil the mixture with upright con-
denser over wire-gauze for two hours. On pouring a small
quantity of the product into water, only the ester, which is a
heavy oil, should separate, but no solid benzoic acid. The
excess of alcohol is now distilled off on the water-bath and the
residue poured into water. Any free hydrochloric or benzoic
acid is removed by shaking with a dilute solution of sodium
carbonate!. On adding ether and shaking, the ester dissolves in
the top layer of ether, which is separated and dehydrated over
calcium chloride. The ether is removed on the water-bath, and
the ethyl benxoate is then distilled over wire -gauze, a few bits of
porcelain being added to prevent bumping. The distillate is
collected between 205° and 212°. Yield, about 22 grams.
C,jHr,COO M + 1 lOC.H™ C0Hf>COOC,H5 + H2O.
Properties. -Colourless, sweet-smelling oil ; b. p. 211° ; sp. gr.
1*05 at 15°.
COHKN'S ADV. p. o. c                                                   P
PRACTICAL ORGANIC CHEMISTRY

Quantitative Hydrolysis of Ethyl Benzoate.—The

quantitative estimation of an ester by hydrolysis is conducted as
follows : a standard half-normal solution of alcoholic potash is
prepared by dissolving 7 grams of caustic potash in about an
equal weight of water and diluting to 250 c.c. with absolute
alcohol. The liquid is allowed to stand overnight in a stoppered
flask and filtered through asbestos
into a clean diy bottle closed with a
cork through which a 25 c.c. pipette
is inserted. The solution is first
standardised by titration against half-
normal sulphuric acid, using phenol-
phthalein as indicator. About I gram
of ethyl benzoate is carefully weighed
by difference by means of the ap-
paratus shown in Fig. 82.

A volume corresponding to about
I gram is delivered into a- round
flask (200 c.c.) by attaching a piece of rubber tubing to the wide
end of the apparatus and blowing until the liquid descends to
the required graduation on the wide limb. Twenty-five c.c. of the
standard alcoholic potash solution is added, and the mixture
boiled on the water-bath with reflux condenser for twenty
minutes.

FIG.  82.

The amount  of free alkali  is  estimated  by  titration with
standard sulphuric acid and the quantity of ester calculated.
Example.—1'355 grams required 15'! c. c. N/2H2S04

15-1 XQ-I50X 100

2x1-1355
See Appendix^ p. 308.

" = 997 per cent.

PREPARATION 100.
ff Acetophenone (Phenylmethylketone, Hypnone),
C6H6.CO.CH3      .
Friedel, Crafts, Ann. Chim. Phys., 1884, 1, 507 ; 14, 455.
30 grms. benzene.
50   „      aluminium chloride (anhydrous).
35    „      acetyl chloride.
ACETOPHENONE

The various reactions, known as the Friedel-Crafts reactions,
arc effected by means of anhydrous aluminium chloride.    The
aluminium   chloride,   being-  very  hygroscopic, cannot  be kept
long, even in a stoppered bottle,  without undergoing- gradual
decomposition.    As the success of the reaction depends entirely
on the quality of the chloride, it should be either freshly pro-
cured, from a reliable firm or resublimed from a retort.    It may
also be prepared on a small scale by passing dry hydrochloric
acid over heated aluminium foil or filings, but the operation is
troublesome  and   scarcely  repays  the   time  spent.    Attach  a
round flask (500 c.c.) to an upright condenser, and bring into it
the aluminium chloride, which should be well powdered, and
immediately cover it with the benzene.    Place the flask in ice-
water, and add the acetyl chloride drop by drop from a tap-funnel,
which  is pushed into the top of the condenser.*    A vigorous
effervescence  occurs,  and hydrochloric acid is evolved.    The
contents of the flask are converted into a brown, viscid mass,
which, after standing an hour, is stirred up and shaken into a
beaker containing ice and water (250 c.c.).    The mass decom-
poses with evolution of heat, and a dark oil separates on the
surface.    The liquid is poured into a separating-funnel and a
little benxene added.    The aqueous portion is drawn off, and
the benzene layer shaken up with dilute caustic soda and then
with   water.    The benzene   solution  is  finally  separated,   de-
hydrated   over calcium   chloride,  filtered,  and distilled.    The
benxene first passes over.    The thermometer then rises quickly
to 195°.    The receiver is now changed, the water run out of the
condenser, and the distillate, which boils at 195—200°, collected
separately.    It forms  a  pale  yellow oil with a characteristic
sweet   smell,   and   solidifies   completely  on   standing.    Yield,
20—25 grams.
C(;H(J + CH3COCl = CUH6.CO.CH3 4- HCL
Properties.—Colourless plates ; m. p. 20° ; b. p. 202° ; insoluble
in water.
Reacfi<ws*—i. Acetophenoneoxime.—Mix together 5
grams of hydroxylamine hydrochloride dissolved in 10 c.c. of
water, 8 grams of acetophenone, and 3 grams of caustic soda
dissolved in a very little water. Add spirit until, on warming, the
solution becomes clear, and boil it on the water-bath 2—3 hours.
PRACTICAL ORGANIC CHEMISTRY

Pour into 100 c.c. water, and extract with ether. Distil off the
ether and crystallise the solid residue from petroleum spirit.
Yield, 8 grams ; m. p. 58-60°. C()H;VCO.CH, + NH,OH.HCl-f-
NaOH - C0H,C(NOH).CH, + NaCl + 3HaO.
2.  Acetophenonesemicarbazone.—Mix i gram of semi-
carbazide hydrochloride with I '5 grams of crystallised sodium
acetate, and dissolve in the smallest quantity of warm water.
Add i gram of acetophenone and sufficient spirit to produce a
clear solution when hot. Continue to heat for a few minutes. On
cooling,  the  semicarbazone deposits   as a yellow, crystalline
mass.      CCH.VCO.CH., + NH,.NH.CO.NH.,HC1 + NaC,H,O2
= C(.H5C(N.NH.CONH,)CH,"'+ NaCl + C2H4Oo.   Theoretical
yield ; m. p. 185—• 188'.
3.  Beckmann's Reaction.—Dissolve  i  gram of aceto-
phenoneoxime in 30 c.c. anhydrous ether, and add gradually
i'5 grams of powdered phosphorus pentachloride.    Distil off the
ether, and add a little water to the residue.    On cooling, crystals
of acetanilide separate.   Recrystallise from water, and determine
the melting point.
1.  CGH5.C1NOH).CH3 + PCI,
= C0H6.C(NC1).CH3 + POO, + HCL
2.  CGH&C(NC1)CH3+ H,0 = C0HflNH.CO.CH3 + HCL
4.  Benzoylacetone (Claiseris Reaction).—Six grams of dry,
!                                powdered sodium ethoxide are added to 20 grams of dry ethyl
i                                acetate, and cooled in water.   The sodium ethoxide is prepared
by dissolving 4 grams of sodium in 40 c.c. absolute alcohol, and.
^                             distilling off the excess of alcohol, first from the water-bath, and
'                             then from the metal-bath, in a current of dry hydrogen, the
temperature of the bath being raised gradually to 200°, until
'         ' nothing more passes over. The white cake is detached rapidly
\                            powdered, and the requisite quantity quickly weighed out and
1                            added to the'ethyl acetate. After standing a quarter of an
j                            hour, 10 grams of acetophenone are added, when sodium benzoyl
|                            acetone begins to separate. A little ether is added, and, after
1                            standing for a few hours, the sodium compound is filtered and
!                            washed with ether. The sodium compound is then dried in
f                            trje air, dissolved in cold water, and acidified with acetic acid.
p                            Benzoylacetoneseparates out. Yield,9—10grams; m.p.60—61°.
IMI'IIKNYLMKTIIANK                          2I3

It behaves towards ferric chloride and copper acetate like ethyl
acetoacetate (see Reactions, p. 84).
, ONa
I.                      CH,.C:   <)C.,ir-+ CH...CO.C,H.
()(', I -I,           "              "
- CH:,.C(C)N;i):CII.(X)'.CuTI. -f 2C2Hf,OH
en,.aY)Na):Cn.C<)C(;H- + C.,H,O,
- cii3.a).ciia.co.c(jiifl + Nac;H:jcx.
See Appcndi.\\ p. 309.
PREPARATION   IOI.
Dipheiiyliiiethane, C(l 11... C11._,. C(JI I.
Cohen, Hirst, Tnuts. Chan. S(n\: 1895, 67, 826.
60 grills. bcn/ene,
30   „       benzyl chloride.
I    „      aluminium-mercury couple.
The benzene is placed in a flask attached to an upright con-
denser.* The aluminium-mercury couple is then added. It is
prepared by pouring a saturated solution of mercuric chloride
on to aluminium foil, which is cut into strips or formed into rolls.
After about a minute, the surface of the aluminium is coated
with a film of metallic mercury. The solution is poured off, the
foil well washed with water, then with alcohol, and finally
with a little benxene. This must he done quickly and the
pieces of couple dropped into the benxene. The benzyl
chloride is added slowly from a tap-funnel inserted through
the lop of the condenser. A brisk effervescence occurs, accom-
panied by a considerable rise of temperature, and fumes of
hydrochloric acid are evolved. When, in. the course of an hour,
the benzyl chloride has been added, the flask is heated on the
water-bath for ten to fifteen minutes. The contents of the flask
are now shaken up with water containing a little caustic soda,
and the benxene solution separated in a tap-funnel. The
aqueous portion is again extracted with benxcnc, and the whole of
the'benzcne solution is dehydrated over calcium chloride. The
benxene is then distilled off, and when the thermometer reaches
iod' the distillation is continued /// wrae^. At 80 mm. cliphenyl-
methane boils at 174—176'. This fraction solidifies completely
2I4                PRACTICAL ORGANIC CIIKMISTKV

on cooling, and is pure cliphenylmcthane ; m. p. 25—26°.
Yield, 14 grams.
QH.CHXl + CflHfl = C(IHflCH2CnMri + HC1.
Properties.—-Colourless   needles;   m. p.  26.......27 ' ; I), p.   262'.
On boiling with potassium clichromate and sulphuric acid it is
oxidised to benzophenone, C0H.-CrLC(!Hr, -h Go =•• C0H.-.CO.Ct;H5
+ HoO. See AppendL\\ p. 312.
PREPARATION 102.
Triphenylmethane, CH(C(!HA):j
Friedel, Crafts, Compt rend., 1877, 145° ; E- '™d O. Fischer,
Annalcn, 1878, 197, 252 ; Biltz, Ber., 1893, 26, 1961.
200 grms. (230 c.c.) benzene.
40     „     (26 c.c,) chloroform.
30     „     aluminium chloride.
The benzene and chloroform are mixed together and
dehydrated over calcium chloride overnight before use. The
liquid is then decanted into a retort connected with an upright
condenser,* and the powdered aluminium chloride added in
portions of about 5 grams at a time at intervals of five minutes
and well shaken. On the addition of the chloride the reaction,
sets in spontaneously, and the liquid begins to boil with evolu-
tion of hydrochloric acid. The aluminium chloride gradually
dissolves, forming a dark-brown liquid. The reaction is com-
pleted by boiling for half an hour on the sand-bath. When.
cold, the contents of the retort arc poured into an equal volume
of cold water, which decomposes the aluminium compound with
evolution of heat, and the free hydrocarbon dissolves in the
excess of benzene with a reddish-brown colour. The upper layer
of benzene is separated from the aqueous portion, and the former
dehydrated over calcium chloride. The excess of benzene is
distilled off on the water-bath, and the dark-coloured residue
fractionated up to 200°. It is then distilled /// tnicito from a
retort without condenser. At first an oil distils, which consists
of impure diphenylmethane. When most of the cliphenyl
compound has passed over, the distillation suddenly slackens.
The receiver is now changed, and the retort more strongly
max/A LI )i«;i i YDK ( ; RKKN                        215

heated.    An orange-coloured oil passes over, which crystallises

in the receive1!*.    The distillation is continued until the distillate                    ,

no longer solidifies on cooling.    A black, resinous mass remains

in the retort.     The crude triphenyl methane in the receiver is

recrystallised from hot ben/ene, with which it forms-ia crystal-                  , , i

line com])ound   of the   formula   C^H^.C,;]"!,;.     This  is  again

crystallised.      By heating the substance on the  water-bath it

loses benzene, and the hydrocarbon is finally crystallised from

hot alcohol.    Yield, 25    30 grains.

Ci U.'l;, ~h 3C,}M,i - CI !(C(iH,), + 3HC1.                                     ! '

/>;v>/v.r//V.y.    Colourless plates ; in. p. 92" ; b. p. 360°.                                  ,

AYfir/vVw.v.   Synthesis of  Pararosaniline.-   Dissolve a
gram of the hydrocarl)on in about 5 c.c. cold fuming nitric acid,                   '

pour into water, filler, wash, dry on porous plate, and dissolve in
5 c.c. glacial acetic acid. Add a. grain of zinc dust on the point
of a knife gradually, and shake up. The colour changes to brown,
and the leuco-base of pararosaniline is formed. It is diluted                    II*

with water and precipitated by ammonia.    It is then filtered and                    ']

dried. < )n gently warming the dry precipitate with a. few drops
of concentrated hydrochloric, acid in a porcelain basin and then                     .,,

diluting with water, a magenta colouration is produced from the                  jiffl

formation of pararosaniline' hydrochloride (E. and O. Fischer).                  'wi

Sec Appendix, p. 312,                                                                                  Jt[

PKKI'ARATION 103.

Benzaldehyde Green (Malachite Green)                          , \   ]

(Telramethyldiaminotriphenylmethane),                                     *' '

/••<-'o Mr,                                                                                                  V I

(').   Kischer, Anmilen, 1883, 217, 250, 262.    ^                              |!
50 grins, dimethyl'miline. •                                                           l\
20     „     ben/a.ldchycle.                                                               -1
40     „     xinc chloride (fused and powdered;.                               ^
A  mixture of the above  is heated on  the  water-bath in a.                  \^
porcektin basin until the smell of benxaldehyde has disappeared                 %V
216               PRACTICAL ORGANIC CHEMISTRY

(4 hours). The viscous mass is melted in boiling water, trans-
ferred to a round flask (ij litre) and distilled in steam until no
more dimethylaniline passes over. On cooling, the base adheres
to the flask and is washed by decantation. It is recrystallised
from absolute alcohol and is colourless. The yield is nearly
theoretical. This is the leuco-base, and is formed according to
the following equation :

/CGH4N(CH3)2
CGH5CHO + 2C0H6N(CH,)2 - CGH5CH/                        +H2O.

It is converted into the colouring matter by oxidation. Ten
grams of the base are dissolved by slightly warming with dilute
hydrochloric acid containing exactly 27 grains of hydrogen
chloride (made by diluting cone, hydrochloric acid with twice its
volume of water and then determining the specific gravity or
titrating with standard caustic soda). The liquid is diluted with
800 c.c. water, and 10 grains of a 40 per cent, acetic acid solution
added. The mixture is cooled with a few lumps of ice, and a
thin paste of freshly precipitated lead peroxide containing exactly
7*5 grams PbO2 (estimated by drying a small weighed sample on
the water-bath) is added in the course of five minutes with
frequent shaking. The product is left 5 minutes, and then a
solution of 10 grams sodium sulphate in 50 c.c. water is run in
and the solution filtered from lead sulphate. To the filtrate a solu-
tion of 8 grams zinc chloride in a little water is added, and then a
saturated solution of common salt until no more of. the dye is
thrown down. It is filtered, and recrystallised by dissolving in
water and adding salt solution. Yield, 80 per cent, of the theory
of zinc salt.

C6H4N(CH3)2

6,o
\CBH4N(CH3)2                   .   \C6H4:N(CH3)2C1

See Appendix., p. 313.

/6432                       /fillff

C6H5CH<                      + 0 + HQ=C/C6H4N(CH,)o      +H2O.

\

.
i                                                     Naphthalene, C10H8
]
,                               Naphthalene is obtained from the "middle oil" in the distil-
j                            lation of coal-tar.    It crystallises in colourless, glistening plates,
Jj                           which have a characteristic smell.
\\                          '   Properties.— -M. p. 80°;  b. p. 218°;   sp. gr. 1-145 at 4°.    It
PIITIIAUC ACID                         217
sublimes readily, and can be distilled in steam.    It is soluble in
most of the common organic solvents.
Rear/ion.—Make strong solutions of about equivalent quanti-
ties of naphthalene and picric acid in acetic acid, or alcohol, and
pour them together. On cooling, yellow, needle-shaped crystals
of naphthalene picrate separate : C1()H8-fCGH2(NO^)3OH ; m. p.
I49°-
PREPARATION 104.
Phthalic Acid, CfiH./cS;g8   \
Friedlandcr, TJiccrfnrbcnftibrikntion^ iv, 164,
15 grins, naphthalene.
120 c.c. cone, sulphuric acid.
7'5 grins, mercuric sulphate.
The mixture of naphthalene, sulphuric acid, and mercuric
sulphate is placed in a retort (300 c.c.). The retort is clamped
\vilh the neck sloping upwards, and heated gently over wire-
gauze with occasional shaking until the liquid surface layer
of naphthalene dissolves.* The retort is now placed in the
ordinary position, with the neck sloping down, to which a con-
denser tube is attached by means of a roll of asbestos paper, or
a lute of plaster of Paris. The end of the condenser tube is
provided with a receiver containing water (too c.c.), and cooled
in cold water.
The retort is now heated (at first cautiously and then strongly)
over the bare flame, and the contents distilled. The liquid
rapidly darkens in colour. At about 250' oxidation begins, with.
evolution of sulphur dioxide, which becomes very vigorous as the
temperature of the liquid rises to the boiling-point. A little
naphthalene first distils, and after a time crystals of phthalic
anhydride appear in the condenser tube, whilst phthalic acid
collects in the receiver. The distillation is continued until the
residue becomes viscid or even dry. The contents of the
receiver, when cold, are filtered and washed, and then dissolved
in caustic soda. Any undissolved naphthalene is removed by
filtration, and the acid rcprecipatccl by hydrochloric acid. The
218                PRACTICAL OKdANK' CIIKMISTKY

acid may be recrystallised from water or dilute at< ohol,    Yield,
about 7 grams.

Properties. — Crystallises in plates with no definite inellin^-
pointj as the acid passes into the anhydride on heating. Soluble
in alcohol and in hot water, slightly soluble in cold water.
Reactions. — Sublime a little of the acid in a trM-tubr or in u
clock glass .covered with a filter paper and funnel. I'ltthulie
anhydride sublimes in long needles, in. p. i.;<v> .
( *( )  .
C,,H4(COOIIV- C.jllt         <) i H,o,
(."()
Heat about 0*25 gram of the anhydride \\ilh 0*5 i,;rani of
rcsorcinol in a tost- tube over a small llame fora !'e\\ minutes,
so that the temperature remains at about .;.«>. i 'ool, dssMiivi:
in dilute caustic soda solution, and pour inin \\.n«-r. .\ ;,;nrn
fluorescence is produced, due to the formation of iluore.,a-w
(p. 187). See Af)pemU.\\ 314.
J'KKl'A RATION    105.
/^-Na'phthalenesulphonate of Sodium, « ',„! IvSt >.;N;t
Merx, Weith, Av., i.S;^, 3, n^».
50 grins, naphthalene,
60     „      cone, sulphurie a< id.
"r,'.
The mixture is heated in a round llask (250 <\(
bath to 160 — 170' for four or five hours. The
poured into a basin of water (r litre j, which is heated up and
neutralised with chalk or slaked lime in the form of a thick
cream. The hot liquid is filtered through cloth, squee/rcl out,
and washed with hot water. The lilt rate is evaporated on Jt
ring-burner until a sample crystallises on cooling. The < rys-
tallinc mass of the calcium Jsalt of naphthah-ne siilplioujr arid
is filtered and well pressed. It is redissolved in hot water, and
a solution of sodium carbonate added, until the < al< sum is
just precipitated. The liquid is again filtered through < loth, or
at the pump, washed and well pressed. Tlu: filtrate ih evaporated
0-NAi'irrnoL

to crystallisation as before. The sodium naphthalene sulphonatc
is separated by filtration, and dried in a basin on the water-bath.
The mother-liquor, on evaporation, yields a further quantity of
the salt. Yield, about 60 grains.

1.     (',,,11,+ ILSO.,-CtoH7S< UI + TU).

2.    2C:IOI I7S( >.,! I + CaO - (C10I l7SO,),Ca+ 1LO.

rwpcrtics.......Koliated     crystals;    soluble    in     water.      See

ppendix, p. 315.

1'RKPA RATION  IO6.

p-Naphthol, C,0!17.OH

Kllcr, Atiim/fti, 1869, 152, 275 ; K. l«'ischcr, Anlcitung s. d.
rg. rrtipiti'titc.

30 ijnns. /^-naphthalene sulphonatc of sodium.
90     „     i'austic sod:i,

The caustic soda and water arc; heated in a nickel fir silver
crucible, and stirred with a thermometer, protected as described                        W
under the preparation of phenol (p. 179).    When the temperature                       V-
reaches 2So', the powdered naphthalene sulphonate is added a                      JM'.I
little at a time.    When all has been added, the temperature is                      '.^t
raised.    At about  300" the mas-s froths up  and  becomes li^'ht
yellow  in  colour,  which  indicates   the   commencement   of the                         r»!
reaction.    The temperature is  maintained at. 3io°-~32o': for a                      s * '
few minutes, and the end of the process is  indicated by the                      ' i L
yellow mass becoming thinner and also darker in colour, and                       *i
separating into two layers.    The stirring  is now stopped and                        ff
the (lame withdrawn.     The product, when cold, is dissolved in          t            l j'|J
H little water, rind acidified with a, mixture of equal volumes of                      ' |
concentrated hydrochloric acid and water.*                                                        tf;
The naphthol is filtered, off when cold, and is recrystalliscd                       l|
from water.    Meld, 15 grains.                                                                              i tf
Cj0ll7S< )3Na -H NaOH - C10I I7(JNa, + Na I ISO.,.                                  ^
»                                         ^\
Colourless leaflets ; m. p. i22r; ; b. p. 286'.                                  ^
PRACTICAL ORGANIC CHEMISTRY

Reactions.— Add to a solution of the naphthol in water a few
drops of ferric chloride. A green colouration is produced, and
after a time a flocculent precipitate of dinaphthol, C^H^O^.

See also Reaction 6, p. 163.

/S-Naphthyl methyl ether.— Dissolve 3'6gramsiS-naphthol
in i2'5 c.c. 10 per cent, caustic soda solution, add 3 c.c. methyl
sulphate, warm the liquid gently and shake vigorously. In a
short time the naphthyl methyl ether separates as a solid mass.
The product is heated for ten minutes on the water-bath, a little
water is added, and the naphthyl ether filtered and washed with
water. It is crystallised from alcohol and deposits in lustrous
plates ; m. p. 70— -72°. The yield is theoretical. It may be
used for analysis by Zeisel's method.

Zeisel's Method. —The method consists in estimating
methoxyl or ethoxyl groups by decomposing the substance with
strong hydriodic acid and eliminating the alkyl group as alky!
iodide. The alkyl iodide is passed through an alcoholic solution
of silver nitrate, which decomposes the alkyl iodide and the
silver iodide is weighed.

The apparatus devised by W. H. Perkin, senior, is shown in
Fig. 83 (Proc. Chem. Soc., 1903, 19, 1370).
It consists of a distilling flask (100 c.c.) with a long neck ; lh«
distance between the bulb and side tube is about 20 cms. (8 ins. .
It is provided with an inlet tube which terminates above the
surface of the liquid and is attached at the other end with a
carbon dioxide Kipp and wash-bottle containing silver nitrate
solution to remove traces of hydrochloric acid or hydrogen sul-
phide. The side tube of the distilling flask is attached to two
small 100 c.c. Erlenmeyer flasks, provided with double-bored
rubber corks. The first bent tube which is attached to the side
tube of the distilling flask is cut off below the cork, the second
terminates just above the surface of the liquid in the first flask
and dips below the liquid in the second. The third or outlet
tube is bent at right angles and is cut off below the cork.
Thedistillingflaskisheated in a basin containing glycerol. The
first Erlenmeyer flask is charged with 20 c.c. alcoholic silver
nitrate, an/} the second with 15 c.c. of the same solution which
is prepared by dissolving 2 grams of fused silver nitrate in 5
#-NAl'JlTIlOL

221

e-.c. uaterand adding 45 c.c. absolute alcohol. An accurately
\v^ii-ine(l i|uantily (0*3 u'ogram ) of substance is inlroducecl in a
cjinall weighing tube into the distilling flask and 15 c.c. of strong
l^yclriodic acid (acid of sp. gr. 17 for Xeisel's estimations can be
purchased). When the apparatus has been carefully fixed
tog-ether the glycerol bath is heated to 130—140''and a slow
current of carbon dioxide (two bubbles a second) is passed
through the apparatus. The temperature of the glycerol bath
js slowly raised until the hydriodie acid begins to boil gently. A
%vhite deposit (a compound of silver iodide and nitrate) begins to

form on the surface of the first flask and gradually settles to
tlie bottom, but usually only a trace appears in the second vessel.
The operation is generally completed in one hour; but before
slopping the process it is advisable to test the vapour passing
through by removing the flasks and attaching the small bent
U-ttibe (shown in the Fig. and containing a little alcoholic silver
nitrate solution) to the end of the side tube. If in the course of
ten minutes no turbidity appears, the operation may be con-
sidered at an end, otherwise it is necessary to connect up the
flask and continue the heating for another twenty minutes.
About 50 c.c. of water are heated to boiling in a beaker (250


222               PRACTICAL ORGANIC CHEMISTRY

c.c.) and the contents of both flasks gradually added and well
washed out with hot water. The white precipitate changes to fhe
yellow iodide and the alcohol is driven off.

When the top liquid is no longer opalescent but clear, the
precipitate is collected in a Gooch crucible and dried and
weighed as described on p. 26.

For volatile substances like anisole this method cannot be em-
ployed.

Example.—0*3150 gram naphthyl ether gave 0*468 gram AgT :

31 x 0*468 x IOQ

= 19*6 per cent.

•;                                                  235x0-3150

I                                 Calculated for C10HrOCH:5:CH3O = 19.6 per cent.

j !                              P-Naphthyl Acetate. — Boil gently 5 grams /3-naphthol and

4 ,                            10 grams acetic anhydride for J hour with air condenser  and

t \                           pour the product into water.    Crystallise from dilute alcohol ;

,VI(I   "4                       m. p. 70°.

'( | j                             A. Gr. Perkin's Acetyl method. (Proc. Chem. Soc., 1904,

' $   '                        2.0,   171).    The   method   consists  in  hyclrolysing the   acetyl

' \ I ,                        derivative in presence of alcohol  and distilling off the  ethyl

^ ¥    '                      acetate and then estimating the quantity by hydrolysis.

The apparatus is shown in Fig. 84.    It consists of a small
distilling flask (200 c.c.) with bent side-tube which is fitted, to n

FIG. S4.
long condenser A tap-funnel is inserted into the neck and the
flask is heated over wire-gauze. About 0*5 gram of naphthyl
acetate is. accurately weighed out of a small sample tube by
NAl'HTllOL

difference and any dust adhering to the neck of the flask washed
down with 5 c.c. pure cone, sulphuric acid and 30 c.c.
pure alcohol, which are slowly run in with shaking. A small
fragment of porous pot is also added. Twenty c.c. half-normal
alcoholic potash (see p. 210) are introduced into the round flask
(200 c.c.) which serves as receiver and 20 c.c. pure alcohol are
poured into the tap-funnel. The liquid in the flask is slowly distilled
whilst the alcohol is delivered drop by drop from the tap-funnel
at about the same rate as the liquid distils. The distillation is
continued until about half the bulk of liquid originally present
in the flask remains. This residue should be quite colourless.
The receiver is now attached to a reflux condenser and boiled
on the water-bath for -1, hour and finally titrated with half-normal
sulphuric acid, using' phenolphthalein as indicator.
The method does not give good results with acetamido-
compounds like acctaniliclc, &c.
K.vtiiiiplc.-.....0*663 gram naphthyl acetate required 7*5 c.c.
N/2 ROM.                "              '
?•; x 0*04 3 x IOQ        f              .
•  -          V          = 23-6 per cent.
2x0-633            °    [
Calculated for C,01!7.O.COCH, ; CjH.,0-23'1 per cent.
Tschttgaeff's Hydroxyl  Method.-........This method  rests
upon the action of hydroxyl compounds on magnesium methyl
iodide by which methane is evolved.
R.OII + Mg/^11-'5 - R.MgI + CH4.                                        fa
The apparatus   is an ordinary   Lunge nitrometer filled with                       \]   ,
mercury, which together with  the attached. Erlenmeyer flask                       5 ',
is  kept  at constant temperature by a flow of water through                        *^| i
an   outer jacket.    The  three-wav cock  is connected with the                       'if* I
*                        •                                            '«  '
Erlenmeyer flask (150 c.c.) by stout rubber tubing1.     A stock                        ff
solution   of magnesium   methyl   iodide   is   first  prepared   by                        V
mixing*   together   in  a   flask   connected   with   a   reflux  con-                        d
denser   100   grams    amyl   ether   distilled,   over   sodium,   9*6                       j,
grams clean magnesium ribbon and 35*5 grams dry methyl iodide                        Ij '
.and a few iodine crystals. After the first reaction is over the mix-                       \;(
ture is heated for i—-2 hours on the water-bath with condenser to                        *>
expel unchanged methyl  iodide, and preserved in a vaselined                       '|  i
stoppered vessel.   About o'l—0*15 gram /3-napUthol is accurately     .                   '^j
224               PRACTICAL ORGANIC CHEMISTRY

weighed in a tube which is of such a length that it rests against
the side of the nitrometer flask. About; 10 c.c. of the reagent are
poured into the flask ; the tube containing the substance, which is
dissolved in a little amyl ether, is slipped in ; the flask is attached
to the side tube of the nitrometer and is then cut off from the
nitrometer tube by turning the tap. A little moisture and
oxygen in the flask are absorbed by the reagent and the pressure
falls. After standing for J hour the nitrometer tube is nearly filled
up with mercury, the tap is withdrawn for a moment to readjust
pressure and the tube then completely filled with mercury. The
tap is now turned so as to establish communication between the
flask and nitrometer tube and the mercury reservoir lowered.
The tube containing the solution of the naphthol is inverted
and shaken. Evolution of methane rapidly occurs and in a
short time the volume remains constant. The volume, tempera-
ture and pressure are read off and the percentage of hydroxyl
calculated.
Extimph.—O'i2o gram /3-naphthol gave 20 c.c. methane at
N.T.P.
20 X   17 X   100 _lo.fr
224O X  O'I2O
Calculated for C10H7OH ; OH = irS per cent.
(Tschugaeff, Bcr^ 1902, 35, 3912 ; Hibbert and Sudborough,
Proc. Cheui. Soc., 1903, 19, 285 ; Zerewitinoff, Ber^ 1907, 40,
2023.) See Appendix^ p. 315.
PREPARATION 107.
OK
Naphthol Yellow,   SO*K|      |      |NO*
\/\/
NO2
Friedlander, Theerfarbenfabrikation, I, 322, II., 215 ; Cain
and Thorpe, The Synthetic Dyestitffs, p. 226.
20 grms. a-naphthol.
80     „     (45 c.c.) cone, sulphuric acid.
4°      55     (j° c-c-) cone, nitric acid (sp. gr. 1*4).
The mixture of a-naphthol and sulphuric acid is heated for
2 hours to 120° and then dissolved in 120 c.c. water.    The solu-
ANTHRAQUINONE      •                      225

tion is cooled to 20° and stirred mechanically whilst the nitric
acid is run in drop by drop. As the temperature should not
rise above 40° it will be found necessary at the beginning to
cool the vessel in a freezing mixture. After the nitric acid&has
been added the stirring is continued for another I hour and the
product is then left overnight. The naphthol yellow crystallises
out and is filtered and washed with small quantities of a cold,
saturated solution of salt. The precipitate is then dissolved in a
large basin of hot water and potassium carbonate solution added
until the liquid gives an alkaline reaction. On cooling, the
potassium salt separates in small orange needles, and is filtered
and dried on a porous plate. Yield, 20—25 grams.
C10H7OH 4- 3H2S04 = C10H4(OH)(S03H)3.
C10H4(OH)(SO,,H)3 + 2HN03 = C10H4(OH)(NO.,)2SO3H
•+2H2SO4.
2C10H4(OH)(N02)2S03H + KSC03 = 2C10H4(OH)(NO9),S03K
+ C02 + H20.
See Appendix) p. 315.
PREPARATION 108.
Anthraquinone, C(JH4<
Graebc, Liebermann, Annalen, SpL, 1869, 7, 284.
10 grms. anthracene (pure).
120 c.c. glacial acetic acid.
20 grins, chromium trioxide dissolved in 15 c.c. water, and
then 75 c.c. glacial acetic acid added.
The anthracene is dissolved in the acetic acid by boiling them
together in a round flask (| litre) with upright condenser over
wire-gauze. The solution of chromium trioxide is then dropped
in from a tap-funnel pushed into the top end of the condenser
whilst the liquid is kept boiling. The operation should last about
an hour. The solution becomes a deep green. It is allowed to
cool and poured into water (500 c.c.), which precipitates the
anthraquinone in the form of a brown powder. After standing an
hour, it is filtered through a large fluted filter, washed with a little
COHEN'S ADV. P. o. c.                                             Q
226                PRACTICAL ORGANIC CHEMISTRY

•

hot water, then with- warm dilute caustic soda and water again.
Yield, 10 — 12 grams.

Sublimation.— A portion of the dry substance may be
purified by sublimation. It is placed (2—3 grams) on a large
watch-glass, which is heated on the sand-bath over a very small
flame. The watch-glass is covered with a sheet of filter paper,
which is kept flat by a funnel placed above. After five minutes
or so pale yellow, needle-shaped crystals of anthraquinone will
have sublimed on to the filter paper.

,CHV                                                /COX

C0H '   I    \CflH4 + 2Cr03 + 6C,H4Oa = CflH4<       >CrtH.,+
XCH/                                               XCO"

Properties. — Yellow needles: m. p. 277 ; sublimes at 250 ;
b. p. 382" ; insoluble in water, soluble in acetic acid, less soluble
in benzene and other organic solvents.

Reaction. — Add a little dilute caustic soda to a small quantity
of anthraquinone, and then a little zinc dust. On heating to
boiling, an intense red colouration is produced, which disappear^

on shaking.    Sodium oxanthranolate, C<5H.,                .

formed,   which   oxidises   in   the   air  to   anthraquinone.
Appendix, p. 316.

PREPARATION 109.

Anthraquinone /^monosulphonate of Sodium,
CGH 4/£°\C0H3.SOaNa + H,O

Graebe, Liebermann, Annalcn, 1871,160, 131 ; A. G. Perkm,
Private communication.
30 grms. anthraquinone.
30     „     fuming sulphuric acid (40 per cent. SO;.).1
The 40 per cent, fuming sulphuric acid is removed from tin;
bottle by cautiously melting it in a sand-bath, and it is then
weighed, out in a flask (£ litre). The anthraquinone is added,
and the flask attached by a cork to an air-condenser. Tin.?
1 As fuming sulphuric acid is difficult to keep In an ordinary stoppered butt I**
without absorbing moisture, it is advisable to coat the stopper with a layer «yf
paraffin wax, and a substantial covering of plaster of Paris above this.
ALIZARIN                                   227

mixture is heated in a paraffin or metal-bath to 150— 1 60° for
8 hours. The dark coloured mass is poured whilst hot into a
large basin containing about a litre of cold water, and boiled
for an hour. The unattacked anthraquinone, which does not
dissolve, is removed by filtration at the pump. The precipitate
is then replaced in the basin and boiled up again with about
\ litre of water, filtered and finally washed once or twice with
boiling water. The combined filtrate and washings, which hayc
a deep brown colour, are evaporated with the addition of 0*2 gram
of potassium chlorate until about vr litre of liquid remains. It
is now nearly neutralised with sodium carbonate solution (about
i 20 grains soda crystals) but not completely, as the sodium s,alt
of the monosulphonic acid is less soluble in presence of acid.
It is therefore convenient to pour out half a .test-tube of the
acid liquid, and proceed to neutralise the remainder. The small
quantity of acid liquid is then replaced. The liquid is evapo-
rated on the water-bath until a scum covers the surface, and it
is then left to cool. The sodium salt of the sulphonic acid
crystallises in pale yellow, silky crystals, and is separated at the
pump. After being washed three or four times with a very little
slightly acid water, it is dried on a porous plate. Yield, 20 — 25
*. grains. A further quantity of the salt may be obtained by
evaporating the mother-liquor, but it is liable to contain sodium
sulphate.

CuHhO,H-H,SO.l=C]4H7O,.SO3H-l-H,O.

Properties. — The sodium salt of the sulphonic acid crystal-
lises, when pure, in colourless leaflets, slightly soluble in cold
water, insoluble in alcohol.

PREPARATION no.

<v         •        n ir /COX- u /OH  a

Alizarin,       ^          C(iH-OH

-\OH
Graebe, Licbermann, Annalcn.Spl^ 1869, 300; Perkin, Engl
Patent, 1869, No. 1948; A. G. Perkin. Private communi-
cation.
20 grins, anthraquinone monosulphonate of sodium.
90     „     caustic soda.
5     „     potassium chlorate.
0 2
228

PRACTICAL ORGANIC C

The caustic soda is dissolved in about half its weight °f water,
and is added hot to the anthraquinone sulphoiiato <^>f~ sodium,
previously mixed into a paste with the potassivn"1"* _ chlorate
dissolved in about 50 c.c. of water. The niixture, wliioli forms
a stiff paste, is transferred at once to a small metal pressure tube
of steel or phosphor-bronze of the shape and dimensions shown

in Fig. 85-1 The mixture fills it
about two-tl^ircls full- ^ A sheet
of asbestos "cardboard iis inserted
between the body n.ri<:l the top
of the vessel, and the meUil lop
is then screwed firmly on. The
pressure tutoe is heat eel Tor three
hours in a paraffin- O1~ oil-bath,
so that the therm oineter in-
serted into tlie inner t vi lj>e, which
contains a little po.riiftln, regis-
ters 190—200°. The cliii-k violet
coloured mass, after cooling, is scraped out niicl di^'^^ted with
boiling water for an hour. Milk of lime is added until the
violet calcium alizarate is all precipitated. Tliis ca.n l^e ,'iscer-
tained in a small filtered sample by adding £t little mi He of lime,
when no violet precipitate should be formed. The prcici pilule is
filtered at the pump and washed with boiling- water until the
filtrate is no longer red. The red filtrate contains a. little: mono-
hydroxyanthraquinone, which may be precipitated. !>>r hydro-
chloric acid. The calcium alizarate . 011 tlie filtor is sus-
pended in a large quantity of hot water, and decomposed hy
adding hydrochloric acid. The alizarin, which. sepn.ri.Ltos as an
orange, flocculent precipitate, is filtered cold, \vashed o.l^out eight
times with cold water, and finally dried and cryst^Llliisecl from
alcohol or preferably cumene. Yield, 10 — i 5 grams.

The thickness of the metal is i cm.
FIG.  85.

-+-61L/X
Properties. Orange needles ; m. p. 28 c> - 290° ; sublimes
completely at 140° without decomposition ; soluble In alkalis
with a deep purple colour (sodium alizarate). . It is reduced to
anthracene on heating with dry zinc dust.
1 The apparatus was made for xu by West's Gas Improvement Co. , 3VZ ilos Platting,
Manchester.
ISATIN                                      229
Reaction.—Make a small quantity of solution of alizarin in
caustic soda, and pour into a beaker containing a strong solution
of alum. The insoluble aluminium alizarate is precipitated as a
red lake. See Appendix, p. 316.
PREPARATION  in.
/co\
Isatin from Indigo,  C,H,<       ^C(OH)
\N x/
Erdmann J. prakt. CJicm^ 1841, 24, ii; Knop, Jahresb.
1865, 580.
100 grins, indigo (in fine powder).                                                              <
SOG.C. cone, nitric acid diluted with 10 c.c. water.
Mix ii|) the indigo into a paste with 300 c.c. of boiling- water
in a large basin. Heat to boiling and remove the flame. Then
add the nitric acid to the hot liquid from a tap-funnel at the rate
of a drop or two a second, so that it is all added in the course                      \
of twenty minutes, and stir well all the time. The mass, which
is at first pasty, froths up, and towards the end becomes thinner.
Moil up for about two minutes, as soon as the acid has all been                      ,. j
added, and then pour out about half the liquid into a second
large basin and add a litre of boiling water to each. Boil up                      !wj
for five minutes, and decant from the floating lumps of tarry                      A.
matter through a large fluted filter paper previously moistened                       •>
with water.    Add another litre of hot water to each basin, boil up,                      L
and filter.     Evaporate the combined red coloured filtrates to                      ft
about i \ litre, and filter again, if necessary, from a further deposit                      ^
of tar.     On cooling, a quantity of red crystals discoloured with                      1« ,
tar will separate.     Filter and  concentrate  the  filtrate.     Re-                      ,^i
dissolve the crystals in the smallest quantity of boiling water,                       |- ;
and let the liquid cool somewhat, so that some  of the tarry                      ,J*
matter may separate ; filter and  evaporate  the  filtrate,  until                       «''•
crystals of isatin nearly cover the surface ; then cool and filter                       l!
off the red crystalline deposit.     A further quantity of crystals                       ',|
may  be  obtained  by  evaporating  the  mother-liquors,  which                       J1
must be frequently filtered from tarry deposit.    The crystals                       f
obtained in this way may be purified by dissolving them in
caustic potash solution, and adding concentrated hydrochloric                        j.
acid  to  the  clear liquid  so  long as a black   precipitate   is                       ^
PRACTICAL ORGANIC CHEMISTRY

formed.     The liquid is then filtered,   and  the  purified   i sat in

completely thrown down in the filtrate with more acid.       The

substance is then filtered and recrystallisecl from water.     Yield,-
about 10 grams.

ClfiH10N.;Ol, + Oo = 2CcH,NOo.

10        1"       ^      J             £               o       »        ^ Jf

Properties.—Red monoclinic prisms; m. p. 201°; solu"ble in
hot water and alcohol.

Reactioji.—Dissolve a few crystals in concentrated sulpl~*ur"lc
acid in the cold and shake up with a little coal-tar benzene- A
blue colour due to thiophene is produced. See Appendix? p- 3r 8.

PREPARATION 112.
CH    CH

r                \SpTT
||       j ^-n
HC\/;\/CH
CH  N
natsh., 18So, 1, 316 ; i SSi, 2. 141; Konigs, Be?~.^ i 8*So,
13, QII.
24 grms. nitrobenzene.
3*8    ,,      aniline.
120    „      glycei-ol.
100   „      cone, sulphuric acid.
A large round flask (i-i-—2 litres) is attached to an upright
condenser. The mixture of nitrobenzene, aniline, glycerol, and
sulphuric acid is poured in and heated on the sand-bath until
the reaction sets in (ten to fifteen minutes), i.e. until white vapours
rise from the liquid. The flask is now raised from the sand-
bath or the burner extinguished, and when the first reaction is
over the contents are gently boiled for two to three hours. The
dark coloured product is diluted with water, and unchanged
nitrobenzene driven over with steam. The residue is m rider
strongly alkaline with caustic soda, and the oily layer (qulnolinc
and aniline) distilled off with steam. In order to remove the*
aniline present, the distillate is acidified with sulphuric acicl, and
sodium- nitrite added, until a sample of the liquid ceases to
give the aniline reaction with sodium hypochlorite. It is then
boiled? whereby the aniline is converted into phenoL The
QUININE SULPHATK

liquid is again made alkaline with caustic soda, and submitted
ton third distillation with steam. The distillate is extracted
with ether, dehydrated over solid caustic potash, and, after
decanting and driving" off the ether, the residue is distilled.
Yield, 40 grains of a pale yellow oil.

C(- 1 i . N II, 4- C.I-I ,(0 II), + O = C0HrN +4H20.

Properties. — Colourless liquid; Ix p. 237°; sp. gr. rioS at
o ; insoluble in water ; soluble in alcohol and ether.

Reactions. — i. Dissolve a few drops of quinoline in a little
hydrochloric acid and add platinic chloride. Orange crystals of
the rhloroplatinate arc deposited (C,,H7N)oH.>PlCl(.H- H2O.

2.  Add to a solution of quinoline in acid, potassium chromate
solution ; the dichromatc, (Cjjfl-NJ.jHoCvoO-, is precipitated.

3.  Add   to  i  c.c. of quinoline   I   c.c.  of methyl   iodide  and
warm.    A   reaction   sets   in,   and  on  cooling',   the  quaternary
ammonium iodide, C,,I 17N.CPL;I, crystallises in yellow crystals.

4.  To a. few drops of quinoline add a solution of bromine in
chloroform.    A   crystalline  compound,  C,,H7N.Bro, is   formed.
See Ap/wntUx, p. 318.

PREPARATION 113.
Quinine Sulphate from Cinchona Bark,

Pclletier, Cavcntou, AMI. C/iim. Phys., 1820, (2), 15, 291.
loo grins. cinchona bark (ground in a coffee mill).
20   „      quicklime.
Slake the quicklime, and mix iL into a thin cream with 200 c.c.
\v:il<T. Pour the lic[iiid into a basin containing the powdered
bark and stir up the mass well. Dry the mixture thoroughly
on the writer-bath, taking care to powder up the lumps that
hall together. When cold place the powder in a flask, pour
over it 200 c.c. chloroform, and let the mixture stand over-
night. Kilter through a porcelain funnel and wash with a
further 200 c.c. chloroform. The chloroform solution, which
has now a faint yellow colour, is shaken up well with 50 c.c.
and again with 25 c.c. dilute sulphuric acid, and then with water
until the aqueous solution has no longer a blue fluorescence.
The combined acid and aqueous extracts are carefully neutralised
232                PRACTICAL ORGANIC CHEMISTRY

with ammonia and the liquid concentrated on the water-bath
until crystals of quinine sulphate begin to form on the surface*.
The liquid is allowed to cool and filtered. A further quantity of
crystals may be obtained from the mother-liquor by evaporation,
but the product is not so pure. The crystals arc purified by
recrystallisation from water. Yield, i to 2 grams, or more,
according" to the quality of the bark.

Properties.—The free base, which is precipitated with sodium
carbonate from a solution of its salts, crystallises with 31•!.,<).
The anhydrous base melts at 277° ; soluble in alcohol and el her,

Reactions,— Use a solution of the hydrochloride prepared by
adding a few drops of hydrochloric acid to the sulphate mixed
with water.

1.   Add to a little of the solution a few drops of iodine solu-
tion ; a brown amorphous precipitate is formed.    This reaction
is given by many of the alkaloids.

2.   Acid  chlorine water and  then ammonia in  excess.      An
emerald green colouration is produced.

3.   Add sodium carbonate solution and then shake with etlu.r.
The free base is precipitated and dissolves in the ether.   Decani
the ether on to a watch-glass and let it evaporate.    Crystals ot
the base remain.

4.   Dissolve in a few drops of acetic acid and .add a Iar;,;e
volume of water.    A blue fluorescent liquid is obtained.     See
Appendix, p. 319.

PREPARATION r 14.

/N
Diazobeiizolimide, C(,H-N'   i;

\N
Phenylmethyltriazole carboxylic Acid,

N.C.H,

N

/\

'         \   r

I

N/              CCII

;i
C.COOH

Dim roth, Her., 1902, 35, 1,029.
30 grms. phenylhydrazine.
45 c.c. cone, hydrochloric acid (in 400 c.c. water).
24 grms. sodium nitrite (in 50 c.c. water).
IMIKNYLMKTIIYLTRIAZOLE CARBOXVLIC ACID    233
The phenylhydrazine and bydrocbloric acid are mixed
together, stirred mechanically and cooled witb a few lumps of
ice whilst the nitrite solution is added, until the test with starch-
iodide paper shows that an excess is present. The hydro-
chloride dissolves, and diazobenzolimidc separates out as an
oil.
/N
C(!n,Nn.NH.,+ nNOo-Cr!I.N<   || +2l-I,O
\N'
Part of the  water is removed by a syphon and the oil is
extracted with ether ; after removing the ether, the diazobenzol-
imide is purified by distillation in steam.    l\ is again extracted
and separated witb ether as before.    Yield, about 25 grams.
4 grms. sodium.
68 c.o. absolute alcohol.
22 grins, acctoacetic ester.
20     „     diazobcnzolimide.
The sodium is dissolved in the alcohol, and to the cold solu-
tion a mixture of the acctoacetic ester and diazobenzolimicle
is added, and then warmed to boiling with reflux condenser.
As soon as this occurs, the tla.sk is removed and cooled, if the
action becomes too violent. After the reaction is over, the
mixture is heated, for an bour on the water-bath with reflux con-
denser, when the contents of the flask become almost solid. The
mass is dissolved in the smallest quantity of hot water, and the
liquid, if neutral, made strongly alkaline and boiled again for an
hour. About 350 r.c. bot water arc added, and sufficient hydro-
chloric acid to precipitate the triaxolc carboxylic acid. It is
filtered and washed with a little water, and is then nearly pure ;
m. p. 155". Yield, about 27 grams.
M.C:,,!!,,                                 N.QH,
//    '             X\
N/    ~r         ,    rHON       "N     C.CH:i + 2C,HflOH.
H/CO.CH,,   "h   ca"f,ONa..... y       ^
N       !         "                          N—C.COONa
CIUCOOCUL,
See Appendix, p. 320.
APPENDIX
NOTES ON THE  PREPARATIONS
PREPARATION  i.
Ethyl Potassium Sulphate.- The combination heuvmi
alcohol and sulphuric acid is not complete, a condition of
equilibrium bcinjj reached before either constituent is com-
pletely converted. The reaction is known as a r/w; •.*•/////• one
and may be represented thus :
GjHr.OH -|- ILSO.j ZI C2I-rflI-[SO.tH-M./),
which implies that the nlkyl sulphate reacts with water, re-
generating alcohol and sulphuric acid. The fret* alky! arid
sulphates are, as a rule, viscid liquids, which cannot IK- <li'»
tilled without yielding the olefme. On boiling with watrr,
the alcohol is regenerated. The salts are used for preparing
various alkyl derivatives, such as mercaptans, th'io-ethers and
cyanides.
SO,,/^^11- -1- KIIS ~- CoHaSir -!•• K,S04
Ktliyl iiu-rcaptaii.
2S(Vr''(JK'iIIfl + K'iS    ~- ((VH:i)^ 'I   2K-.SO.!
Ethyl tliio-cthcr.
S('}y\ ()KyIIr> '  KCN """" (:i!n^:N •'• K^S()»
Ethyl cyanide.
Compare the action of sulphuric acid on phenol fseo Trr-p.
74, p. 177).
PREPARATION 2.
Ethyl Bromide.-—The replacement of the hydrogen by
halogen (Cl, I5r) may be effected by the direct action of tin-
halogen on the paraffin.
QJIG + CL, = C«IT0CI + IICL
APPENDIX                                    235

A simpler method is to replace the alcohol hydwxyl by halo-
gen by the action of hydracid (HC1, HBr, HI),'
C,Hf)OII + HC1 = C2n0Cl + H,0.
Or by that of the phosphorus compound (POL, PBr3, PI3),
3C,H,OH + PCL = 3C2II5Cl + P(OII),.
The preparation of ethyl bromide may be taken as an ex-
ample of the first method, in which the hydracid is liberated by
the reaction,
KBr + II2SO4 = II Br + KIIS04.
A further example is that of isopropyl iodide: see Prep. 31,
p. no, in which the hydriodic acid is obtained by the action of
water on phosphorus iodide,
PL, + 3HoO = 3III + P(OII)3.
The action of II Cl is much more sluggish than that of HBr
or III, and in the preparation of ethyl chloride a dehydrating
agent (ZnCL) is usually added to the alcohol, which is kept
boiling whilst the HC1 gas is passed in. In the case of poly-
hydric alcohols, all the hydroxyl groups cannot be replaced by
Cl by the action of HC1. Glycol gives ethylene chlorhydrin and
glycerol yields the<lichlorhydrin (see Prep. 32, p. HI). The use
of IM>r;j, PI3 does not necessitate the previous preparation of
these substances. Amorphous phosphorus is mixed with the
alcohol, and bromine or iodine added as in the preparation of
methyl iodide (see Prep. 6, p. 68). PC15 or PC13 will always
replace OH by chlorine in all hydroxy-compounds, including
phenols, on which HCl does not act.
The alkyl halides are utilised in a variety of reactions,
examples of which are given, ethyl iodide being taken as the
type.
r. Agucoits potash or water with metallic oxide (Ag\,O, PbO)
yields the alcohol (see Prep. 87, p. 195),
Coiirj + KOII = c.2n,oir + KI.
2.   Alcoholic potash gives an olefine,
CoHr,I + KOII = C2H.t + KI + HoO.
3.   Sodium alcoholate gives an ether,
ji = C2HBOC.JIS + NaL
236                PRACTICAL ORGANIC CIIKMISTRV

4.  Alcoholic ammonia forms a mixture of primary, secondary
and tertiary amines,

C,H,I -I- Nil, - CJIr.NU,  i   III
2CoIIfiI  I- Nil, =-. (C.JUoNil   I  2III
SCJIfll -i- Nil, - Coil.-,):, N I  3III.

The tertiary amines unite with the alkyl iodide to form the
quaternary ammonium iodide, which is produced at the same.
time as the other products.

(Col Ia).,N -h QI r,I = (CVi I C)4NI .

5.   Potassium cyanide forms alkyl cyanide,

cyi,, i + KCN ^ caiisCN i- KI.

6.   Potassium hydrosulphidc gives the mcrcaptan,

cjirj -i- Ksir - cjifiSir + KI.

7.   Potassium sulphide forms the thio-ether,

2C«II5I -I- IwS - (C,Iln)oS  !   2KI

8.   Silver nitrite jj'ivcs the nitro-paraffm,

CoIIrJ -|- Ai;-N(X ~ CjHnNC)., -\- Agl.

9.   Silver salts of organic or inorganic acids yield the alkyl
esters,

aCJIrJ -I- A&jSO.! -- (CJIr,)oS(), -I- 2Aj;I.

PREPARATION 3.
Ethyl Ether.— -This reaction is of a general character. P»\'
usinj4" a different alcohol in the reservoir from that in the* flask,
a mixed ether may be obtained. Thus, ethyl alcohol and amy'l
alcohol may be combined to form ethyl amyl ether,
QiiflOii   + iraso4    rsCgiir.so.jir -i- ir,,o.
cvrl)nso4 + cr)nuoir = cjilocvjin -i- fi.so,.
That the sulphuric acid acts in the above manner and not
merely as a dehydrating agent appears not only from t In-
formation of mixed ethers, but also from the fact that the
sulphuric acid may be replaced by phosphoric, arsenic and
benzene sulphonic acids,
APPENDIX                                     237

The ethers are also formed by the action of sodium alcoliolatc
on the alkyl iodide (Williamson),
C,ll;,()Nu -|  C,IIr,T = C,Ha.O.C2IIs -I- Nal,
and by this method mixed ethers may also be prepared.
The inertness of the ethers arises probably from the fact
that the whole of the hydrogen present is united to carbon.
Note the action of sodium and PCI- on alcohol and on ether.
The ethers are not decomposed with PCI.-, except on heating,
when they give the alkyl chlorides,
(C,II,).,0 -I- PC!r, ~- 2C>II,Q -f- POCL
Hydracids, especially 111, have a similar action— .'
(tyU-P -I- 2111 - 2CjII,,I -I- 1I20.
1 lot, strong sulphuric; acid breaks up ether into ethyl sulphuric
acid and water,
(Coiy-jO |  2ll,S()., ::~ 2CoIIrj.SO4IL -|   ILO.
Compare the action of caustic alkalis on ethers, esters and
anhydrides.
/Vis               /C'-jHr,                 ^CO.CIL
O                         O                           O
Vui.-,            ^co.cii..,           N.:o.cir:i
Diclliy! ether.              Kthyl acetate.             Acetic auliytlriclc.
1'RKl 'A RATION     4.
Bthylene Bromide. -The formation of olefmcs by the
action of cone. HoSO., and other dehydrating agents on the
alcohols is a very general reaction.    Among the higher alcohols                 \<
the action of heat alone suffices ; celyl alcohol, C1(il lr;1(), gives                    }
cetylene, C1(I,M;,.>, on heating.    The olefines are also obtained by                   ,J(
the   action   of   alcoholic  potash  on  the   alkyl  bromides  and                    * ,i •
iodides,                                                                                                               • || ,
CJIfiUr -I- K(JH =.- C3ir4 4- KBr -I-11.0,                                          L j
and by the electrolysis of th« dibasic salts ; potassium succinalc                    »
'gives ethylene,                                                                                                \\
CoIUax^KJo = Coll., -I  2CO, + K,(II,).                                         I
The olefines combine with :                                                                               |i
(i)  Hydrogen in presence of platinum black, or finely divided                    111
nickel (see Prep. 78, p. 181).                                                                             I
CII«:CIIS + II,j = CII3.CIIa.                                                  ^
Ethvlewu.                      Ethane.                                                                   ^
PRACTICAL ORGANIC CIIEMISTRV

?! i

if *. i

(2)  The hydracids (HC1, HBr, HI), in which case the halogen
attaches itself to the carbon with the least number of hydrogen
atoms,

ClIa.CH:CII.j + HI = CII;,.CIII.CH:!.

Propylt'iiL'.                    Isopopyl iod'de.

(3)  The halogens (Cl, Br, I),

CII,:CII2 + Go = CI I,C1.C1I,G.

Ethylene.                      Ethylene chloride.

(4)   Cone, sulphuric acid,

,ou         /ocir.,.cn..

CIIo:CIU+(XS<        = OoS<

X)ii     " xoii

Ethyl hydrogen sulphate.

(.5) Hypochlorous acid,

ciL:Ciio -f- iioci = cri2on.cii2ci.

Ethylune clilorliydrin.

Potassium permanganate oxides the olefine, forming in the
first stage the corresponding glycol. By further oxidation the
molecule is decomposed by the parting of the carbon atoms at
the original double link,

CIIS.CII : CILj + IUJ + O = CLI.^CIIOII.Cn.,011.

Propylcue.                                          I'ropyL'iie ylycol.

CIIa.CIIOLI.CllaOII -I- 20, = CII;,,COOir + CO,  I  2lloO.

Acetic acid.

Alkylene chlorides and bromides with both halogen atom-,
attached to the same carbon are obtained by the action of
PC15 and PBrfj on aldehydes and kctones.

cii3.co.cn3 + pcia = cii:i.ca,cir:j +

/3/3-Dichloropropiuie.

PREPARATION 5.
Acetaldehyde.—The formation of aldehyde from alcohol
probably occurs by the addition of oxygen and subsequent
elimination of water,
CH3CMaOII + O = CII3.CII(OII)a = ClLj.CCUl  I- II,<X
The aldehydes may also be obtained by the reduction of acid
chlorides and of anhydrides in some cases, but the method is
rarely adopted. Aldehydes can only be obtained directly from
APPENDIX                                   239

the fatty acids by distilling the calcium salt with calcium form-
ate ; but in no case by direct reduction, unless in the form of
lactones,

{Cira.COO).jCa  I   (HCOO).jCii = 2CIIS.CO.II -!  2CuCOa.

The aldehydes are readily reduced to the alcohols. Charac-
teristic properties of the aldehydes are the formation of aldehyde
ammonias, Schiffs reaction, the reduction of metallic salts and
the production of ticc/tt/s by the action of alcohol in presence of
hydrochloric acid jjas (E. .Fischer).

CILj.CO.ll -I   2C'.,lIaUII - CII,,CII(0(\,nr<), -I- 11..O.

Acutlil.

They also polymerise readily. These reactions should be com-
pared with those of ben/aldehyde (I 'rep. 88, p. 196). There are
many reactions which are common to both aldehydes and
ketones, /.*'., to all substances which contain a ketone CO i^roup.
Such, for example, are : d) The formation of an additive com-
pound with sodium bisulphite.

(2)  The action of .PCI.-, which replaces oxygen by chlorine,

/CO -i- PC1;, --   /CCL -I- POCLj.

(3)  The formation of a cyanhydrin with hydrocyanic acid,                       J°

\   ,             ,        \    , ,/MH                                               j^

which on hydrolysis yields a hydroxy-acid.

(4)  The formation of an oxime with hvdroxylamine (see Preps.
9, p. 71, and 89, p. 197).

(5) The formation of a phenylhydrazone will)   plienylliydr-
axinc.



O -K Il2N.NII.CflH0 ->C:
240

PRACTICAL ORGANIC CII KM 1STRV

<•
i, f

(6) The formation of a semicarbazone with semiearba/.ide
(see Prep. 100, p, 212).

Vx) -I-  II,N.NI1.C().N!I,        Nr:N'.NU.C()NII,  i   II,O.

Both aldehydes and kctones readily undergo <w/</<y/.v<f//v//
and a ^reat variety of syntheses have been effected in this way
(see Preps. 94, p. 204, and 103, p. 215).

The aldehydes unite with '/.inc. alkyl i \Vaxnrn and mag-
nesium iilkyl halide ((iri^nard, see p. 206; to form additive com-
pounds, which decompose with water, yielding secondary
alcohols.

,0/nCH..

en.,, co. 1 1 -i /n(cii.,),, - cn,.cnv

Vn,

XCI I:,

,  |  CII.

C 1 1. -CO. II   !   M<'('H..I .- CH,.CiK

CIL.CIK'

Acetaldchydc, in presem:e of HClj polymerises, forming
aldol. With xinc chloride the reaction jjoes a step further and
crotonaldehyde is formed,

cir-.con i- e ii;,. co 1 1 ..- cir.

...... cii;..cH:Cii.coij i n,,p.

Crotoiutltlehydt:.
PRKPAKATiON   6.

Methyl Iodide.— Read notes on Prop. 2, p. 234.

PREPARATION 7.

Aniyl Nitrite.-— The nitrites of the general formula
R'.O.NO are isomeric with the nilro-parafilns K'NO.,. Whereas
the nitrites are liyclrolysed with KOI I like other esters into the
alcohol and the acid,

CjIlfiONO  I   KOI I    - C.Jl.,01!   !   KNO,,
and arc decomposed by reducing agents into the alcohol and

1
APPENDIX

ammonia (and in some cases hydroxylamine), the primary nitro-
paraffins arc not hydrolysed by potash, but dissolve, forming
the soluble potassium salt, and on reduction give the primary
ami no,

CJ1;,N(X i- 3IL = QjIIgNILj + 2lI30.

Amyl nitrite is tised in the preparation of dia/o-salts (see Prep.
62, p. 161).

PRKl'A RATION   IO.

Acetyl Chloride.-- Either PC1;{ or PCI- are almost in-
variably used in the preparation of acid chlorides. In the case
of PCI- only a. portion of the chlorine of the reagent is utilised
(see Prep. 98, p. 208), POC1:J being produced in the reaction,
The use of one or other reagent is determined by the nature of
the product. If the latter has a low boiling-point the trichloride
is preferred, if a high boiling-point, the pentachloride may be
used and the oxychloride expelled by distilling /// vacua from a
water-bath (see Prep. 16, p. 85). The pentachloride is more
frequently used in the preparation of aromatic acid chlorides,
hut there arc occasions, which experience can only determine,
when the trichloride is preferable.

Phosphorus oxychloride and the sodium salt of the acid can
also be used.

2(:ii:,.(.:(K)Nji i poci3 -2rn.,coci + NUPO,, -i- NuCi.

Also thionyl chloride, SOC1,,, may often be used with advan-
tage in place of the chlorides of phosphorus,

I + SOCL -C

Acid chlorides react with alcohols and phenols, and in general
with substances containing a "hydroxyl " (OH) group. Acid
anhydrides have a similar behaviour, and both substances may
be used in determining the number of such groups in a
compound. Thus glycerol forms a triacctyl derivative, whilst
glucose yields a pentacetyl compound. By hydrolysing the
acetyl derivative with alkali, and then estimating the amount of
alkali nt'iilralised by titralion, the number of acetyl groups can
be estimated (see p. 222).
The presence of the "aniino" (NTL) group is determined by
a similar reaction.
The synthesis of aromatic ketones may be effected with the
CO HUN'S ADV. P. O. C                                                                 R
PRACTICAL ORGANIC CHEMISTRY

acid chlorides, using the Friedel-Crafts' reaction (see Prep. 100,
p. 210), also of aliphatic ketones and tertiary alcohols with zinc
methyl and ethyl, &c. (Butlerow) or magnesium alkyl halicle
(Grignard).

/OZnCH3
(i)    CH,.COC1  +  Zn(CH3)o =  CH3.C~-C1

\CH3

OZnCH,                                            xCl

CH, + Zn<

XOI

•OZnCI-Ij          /CH3

(CH3),, = CH3.C^-—'

yOZnCH3

CIL.C^Cl         °+ HoO = CH,.CO.CH, + Zn<        + CH4-

XCH;!                "               ^ Acetone.   '           XOH

:nCH3        /

(2)    CIL.COC1 + 2Zn(CHA, = CH,.Cc-CH.,        + Zn<

\CH;        xci

= CH3.C(OH)(CH3)a
^CHo                         Tertiary butyl alcohol.
An additive compound with zinc methyl is formed, in the
first reaction with one molecule, in the second with two mole-
cules, and the product in each case is then decomposed with
water. The reaction with magnesium methyl iodide is
similar.
PREPARATION 11.
Acetic Anhydride.—The anhydrides may be regarded as
oxides of the acid radicals, just as ethers are the oxides of the
alcohol radicals, and, like the ethers, both simple and mixed
anhydrides may be prepared. The latter, however, on distilla-
tion decompose, giving a mixture of the simple anhydrides.
C2H,0\0 _ C,H,0\0     C3II80\0
2C5H90/U ~ C,M80/U + C5H90/a
Anhydrides may also be prepared by the action of POC13 on
the potassium salt of the acid in presence of excess of the
latter, the reaction occurring in two phases:
2cri:..cooK + POCL.    =2Ci-i:l.coci + KPO:! +KCI.
CI-L.COOK + CJLOC1 = (CoH,O),O + KC1. '
In addition to the reactions described under the Preparation,
the anhydrides undergo the following changes :
i. With HC1, HBr, and HI they give, on heating, the acid
chloride and free acid,
(CH3CO)2O + HC1 = CH8COC1
APPENDIX                                       243

2.  With Cl they form acid chloride and chlorinated acid,

(ClI3CO)oO  I- Cl, = C1I3COC1 + CHXi.COOH.

3.  With Na amalgam they are reduced to aldehydes.

PREPARATION 12.

Acetamide.™ The acid amides, or simply amides, corre-
spond to the amines, being ammonia in which hydrogen is
eplaced by acid radicals, and, like the amines, exist in the form
of primary secondary and tertiary amides. The following
methods are used for obtaining the amides-, in addition to that
described under th'j preparation :

i. The action of ammonia  on  the acid chlorides or  anhy-
drides (see Prep. 98, p. 209).

CILj.CO.Q  !- 2N1L, = CILj.CO.NlIo + NH4C1.

"'  2NII;J = CII:i-CO.NLI3 -I- CII3.COONH4.

r

2.  The action of ammonia on the esters (see Prep. 26, p. 102).
CIJ:,.C()OGjII5 -I- Nil,. = CILj.CONIIo + C2H5OII.
3.   Partial hydrolysis of the cyanides by cone, hydrochloric
or sulphuric acid,
CII:{CN + II,O = CILj.CONIIo.
The alkyl amides or substituted ammonias, with both acid
and alkyl radicals, also exist, and are formed by the first two
of the above reactions and by heating the salt of the amine
(see Prep. 54, p. 151).
CILj.CO.cn NII2GjlI0 = CII3.CO.NHGjHD + HC1.
Acctethylamide.
CII:,.COOIT.NII3CttIIfl   = CII3.CONH.CBII0+ H.,6.     '     ^
Aniline acetate.                            AceLanilicle.
With the exception of formamide, which is a viscid liquid, the
majority of these compounds are crystalline solids. The lower
members are soluble in water, and they all dissolve in alcohol
or ether. Many of thorn distil without decomposition. They
are neutral substances uniting with both mineral acids and
a few of them with caustic alkalis and alkaline alcoholates
to form compounds which are rapidly decomposed by water.
The hydrogen of the amido-group is also replaceable by
R 2
244               PRACTICAL ORGANIC CHEMISTRY

metals, and derivatives of .acetamide of the following formulae
are known :

CH3CONHNa, CHa.CONHAg, (CH3.CO.NH)2I-Ig.
They are converted by nitrons acid into the organic  acid,
and in the case of substituted amides into nitrosamides,
CH3CONH2 + UNO,'         = CH,.CO.OII + N2 + H2O.

CM3.CO.NHC8H5 + HNCX = Cri.,.CO.N(NO).Q;lI5 + IIaO.

Acetanilide.                                   Nitrosoacetanilide.

With the latter class of substituted amides, PC16 forms the
imidochlorides, a reaction which is usually formulated in two
steps,

CH,.CO.NHC,H- + PC13 = CH8.CC12.NIIC,,H5 + POC1«.
CII3.CCl2.NIICdII3 = CHyCCl : NCGII5 + 1IC1.

The substituted amides give both imidochloride and the
cyanide with PC15,

CII3.CONH2 + PC1S = CH3.C^QH + POC1;{ .+ IJC1.
CHs.C/'Q1"1 = CH,.CN + I LCI.

PREPARATION 13

Acetonitrile. — The various reactions by which the nitrilcs
or alkyl cyanides are obtained have already been mentioned
in one or other of the previous notes, but they may be
recapitulated.

i. By the action of KCN on the alkyl iodide or alkyl
potassium sulphate,

C.2H,I + KCN = CaIIsCN + KI.

2.   By the action of PC15 (as well as P2O5) on the amide,
CH3.CONI-L + PC15 = CH,CN + POC1, + 21IC1.
3.   By heating the aldoxime with acetic anhydride,
CH3.CH : NOII + (CH3CO)2O = CILCN + 2CIKCOOH.
They are compounds which are, for the most part, insoluble
in water, possess an ethereal smell, have a neutral reaction, ancl
may be distilled.
API'KNDIX                                        245

The fact that they arc eminently imsaturated compounds is
evidenced by their general behaviour towards a great variety
of reagents.

1.   On reduction they give the primary amine (Mendius),

CM1..CN   1  2llo- CIi:!CII.,NIL,

2.   With HC1, ITIir, and HI they form imidohalides (Wallach),

CllnCN  I  HC1 -Cll,,

//{S!111.

3. With alcohol and II Cl they form the hydrochloride of the
imidoethers, from which caustic alkali liberates the base
(Pinner),

CII..CN i c,Mnon -i i in -cM.x

Cll;,C      ;(;1Ip      I   NaOIl ..... (:il:,CUr-f  NaCH   II,O.

These imidoethers unite with ammonia and amines and form
the amidines,

-

4. The latter are also formed by the direct action of ammonia
on the cyanide,

5. I lydroxylamtnc unites with the cyanides, forming armd-
uximes,
ni.,.CN  I- NlUm - Cn:{.t;<X^jjH.
0. With H.,S the; thiamides are formed,
ni.,.cN i u,,s - cn:,.cs.NH2.
PRKI'ARA'l'ION   14
Methylamine Hydrochloride.- -This reaction, which
yields the primary amine, is applicable, not only to the aliphatic,
but also to the aromatic amides. The formation of anthranilic acid
from phthalimide is a process of technical importance. By the
246               PRACTICAL ORGANIC CHEMISTRY

action of bromine and caustic potash, phthalaminic acid is first
formed, which then yields the ammo-acid,
/COX                                   /CONHj,
C6H4<        >NII + HoO = CBH4<
NrCK                 ~                  XX)OH
xCONHo                              /CONHBr
C6H /            " + Bro      = C6H4<                  + HBr.
XCOOH                              XCOOH
xCONHBr                             ..NCO
QIV                        = CflH/          + IIBr.
XCOOII                                XCOOH
/NCO                                  /NHo
C6H4<;             + HoO      = CJI4<        "      +• CO.,.
XCOOII        "                      \COOH
The primary amines may also be obtained by the following
reactions :
1.  Action   of   alcoholic  ammonia  on   the alkyl iodides   jincl
nitrates,
C2HSI + NIT8 = C2H5NH2 + HI.    (Hofmann.)
Secondary and tertiary amines are also formed (see p. 156),
C2HSONO2 + NH3 = CoH5NIIo + IINO«.    (Wallach.)
2.  Reduction of the following classes of compounds :
nitro-compounds
cyanides
oximes
phenylhydrazones
C2H5NO2 + sH2 = C2H,NH2 + aH2O.    (V. Meyer.)
C2HaCN  + 2lI3 = CoH.CHoNIio.    (Mendius.)
CH3.CH:NOH + 2H2 = CH3.CH2.N.ri2 + H2O.   (Goldschmidt.)
CH8.CH:N.NHCGH5 + 2H3 = CH3.CH2.NH2 -f CflII5.NIIo.    (Tafel.)
3.   Hydrolysis of the isocyanides with cone. HC1, which occurs
in two steps :
C2H5NC + HoO = C2HBNII.COH
C2H5NH.COH + HoO = C2H5NH2 + HCO.OIT.
Th- three classes of aliphatic amines (primary, secondary, and
tertiary) may be disting'uished by their behaviour with nitrous
APPENDIX

acid and alkyl iodide. The primary amine is decomposed with
HNO.,, forming the alcohol, and nitrogen is evolved,

CJlr.NIlo I   UNO., - GUI../'.)!!: -I- No -[- II.O.

The secondary amine forms the nitrosamine, insoluble in water
(Coiy,NII   |   UNO.,- (C.II-^N.NO -1-II.p.

I JiethyliutrnsrumiiL'.

The tertiary amine is unacted on by nitrous acid, but, unlike
the other two, unites with an alkyl iodide and forms the
quaternary ammonium iodide (I lofmann),

(<UIr,):,N I- CH:1I --- (Coirs):,NCIT,,T.>

TrK'thyliuethyhunmomum iodide.

The behaviour of nitrous acid with the aromatic amines is
somewhat different (See Preps. 60, p. 157, and 62, p. 161).

The primary amines may also be distinguished from second-
ary and tertiary amines by the isocyanide reaction (p. 150), which
consists in heating the amine with a Itttle chloroform and alco-
holic potash solution. An intolerable odour of isocyanide is
emitted,

Coilr.NHo 1- CIICL. -I- 3KOIT ™ C«MflNC + 3KC1 + 3lU).

PREPARATION   15.                                                               Ill3

Ethyl Acetate. —Esters may be obtained by the direct action
of the alcohol on the acid as in the case of methyl oxalate.
(Prep 26, p. roi). A certain quantity of ethyl acetate is also
obtained from ethyl alcohol and acetic acid, '-but the action, which
is a reversible one, stops when a certain proportion of the con-
stitucnts have (-ombined (p. 234). It is represented thus :

c,n,()ir i c:n:,.(:oon^;cii3.coocviB + n,o,                           /,
which signifies that the ester and  water react and regenerate                   f^
alcohol and acid, whilst the reverse process is in operation.    P>y
removing the water as it is formed by means of sulphuric acid
or by distillation, this condition of equilibrium is disturbed and
the reaction is completed.    This does not, however, explain the
fact, first discovered by Scheele and afterwards investigated by
Fischer and Speier (see  Prep. 99, p. 209), that a very limited                   f\
quantity of  cone, sulphuric or hydrochloric acid will produce                   fe   '
248               PRACTICAL ORGANIC CHEMISTRY

the same result. According to Henry the reaction with HC1
takes place in several steps,

CHa.COOH + C,H,OH = CH3C(OH)2OC2Ha.
CH3.C(OH)oOC2II5 + HCl = CH3C(OH)C10C2H3 -I- H,O.
CH3.C(OH)ClOCoHn = CH3.COOC2H5 + HCl.

Other methods for the preparation of esters are by the action of
alcohol on the acicl chloride or anhydride (see Reactions, p. 75),
or by boiling' up the dry powdered silver salt of the acid with the
alkyl iodide,

CHa.COOAg + C2H5I = CH3.COOCJIn + Agl.

The esters are, for the most part, colourless liquids or solids of
low m. p., with a fruity smell and insoluble in water. They are
hydrolysed by potash (most readily with alcoholic potash) and
give amides with ammonia,

.CH3.COOC3H5 + NH3 = CH3.CONH2 + C2H5OH.
Acetamide.

PREPARATION 16.

Ethyl Acetoacetate. -The explanation of the manner in
which this substance is produced has been given in the account
of the preparation. The result was arrived at, not by the isola-
tion of the intermediate compound formed by the union of
ethyl acetate with sodium ethylate, but by analogy with the
behaviour of benzoic methyl ester with sodium benzylate, which
gave the same additive product as that obtained by combining'
benzoic benzyl ester with sodium methylate, showing that such
combinations could occur,

/ONa

-3
\OCHo. CaHB
Also by the fact that sodium only attacks ethyl acetate in
presence of ethyl alcohol, although the quantity of the latter
may be very minute. Similar reactions have been effected
with either metallic sodium or sodium ethylate by Claisen,
APPENDIX

249

W.   Wislicenus  and   others, of which   the  following  examples

must suffice ;                                                                     «!

•

;,ITn ~ QJ Ir,CO.CIL,COOCJir>

Arctic rsirr.              -HvmmyUmnxoii: -estcfP      -f C0HP)OH.

K'OOCJlr,  I   CI !....('( K><\,1 1,,       .-  ILCCU'IUCOOCoIlr,

|M,niii<:<-st.-r.              Acvlir CSKT.                     l'Wmyl:u:«:tic ester.     " -| 'C

Gjiir,oH.
- (:.,iiri(xx).c().cii.,.cx)oc,iir,

1 I:,.( '< X )G,I Ir,        <>x.'ilylaa>ti<: estc-r.        "-|-  C,l 1^011.
AtK-tiiM-stcr.'

From this it would appear that condensation might always be.
effected between an ester on the one hand and a compound
containing the group CIL.CO on the other. This seems very
generally to be the rase, and Claisen has succeeded in pro-
ducing condensation products between esters and ketones or
aldehydes containing this group. (See Prep. 100, p. 212.)

The formula for ethyl aeetoacetatc would imply the properties
of a ketone, a view which is borne out.by its reduction to a
hydroxy-acid,

cii:,.c:iion.(:iTa.cooc,jTB,

/3-Hycln>xyl»utyri<: ester.

and by its behaviour with phenylhydra/.ine and hydroxylamine.
The latter reactions give rise to the formation of the usual
phenylhydraxone and oximc, whilst a molecule of alcohol is also
removed resulting in a closed chain, in the former case phenyl-
methylpynizolone, and in the latter methylisoxazolone being"
formed,

CII.{.CCIIo.CO

I                                             ' II    " I

N-------O

Phriiylnifthylpyr.'i/olune.                    Methylisoxa/olone.

The "mcthylcnc" group (CH2) standing between two CO
groups, such as occurs in acetoacetic ester, is characterised by
certain properties, which are shared by all compounds of similar
structure, vi/., by their behaviour towards nitrous acid, diazo-
benxcne salts, and metallic sodium or sodium alcoholate.

The first reaction leads to the formation of isonitrosoacetone,

cn.,.co.cii,,.cooa,irB + UNO., = CII.,.CO.CTT:NOII + co.,
+ CoII5OII.
250

PRACTICAL ORGANIC CHEMISTRY

The second yields, in acetic acid solution, formasyl derivatives,
CHUCO.CHo.COOCoH, -t- CrII,N,Cl = CM ..CO CH:N.NH.Q.II

' '                +"co2-!-c2r-isOH +

CH3.CO.CH:N.NriC,5lI5 + C0rir>N2Cl

- ri^T rn r/N:N-c«IT«     i-

- ^L5.co.c^N<N1LCyIr_ +

Acetyl cliphenyl formnzyl.

The third is capable of the utmost variety, since the sodium
in the sodium compound may be removed by the action of :
i. Iodine,   which  leads  to  the  formation   of   acetosuccinic

ester,

CHo.CO.CHNa.COOCoII,

"   '

CH3.CO.CHNa.COOC.2irs

CH,.CO.CII.COOCJIr

L, =       '        |              ~   '+ 2NaI.

"     CH^.CQ.CII.COOCJL,

Acetosuccinic ester.

2.  Alkyl  iodide,  whereby two  atoms  of hydrogen  may   be
successively replaced by the same or different radicals,

CH.,.CO.CHNa.COOCoH, + CH,I      = CH3.CO.CH(CIL)COOC,I I*

'+ Nal.

CHn.CO.CNa(CFI,}.COOCoII5+ CH3I =CH^CO.C(CIL,).,COOC>I U,

' + Nal.

3.  Acid chloride, which is of similar character to the fore-
going process, but gives rise in some cases to the simultaneous
formation of two isomeric compounds, a fact which at one  time
threw considerable doubt  on  the ketonic character of acelo-
acetic ester.    Thus chloroformic ester and sodium acetoacetic
ester produce the following two derivatives, of which the second
predominates :

CH3.CO.CH(C02C2H5)2.

Acetylmalonic escer.

CHS. C(OC02C2Hs) 'CH. COoC2I I5.

jS-Carboxethylacetoacetic ester.

The synthetic capabilities of this compound are not yet
exhausted. Acetoacetic ester and its alkyl derivatives undergo
decomposition in two ways, according to whether dilute
alkalis and acids or, on the other hand, strong alkalis are
employed.
APPENDIX

251

1.  With dilute aqueous or alcoholic caustic alkalis, or baryta,
or sulphuric acid, a ketonc is formed (ketonic decomposition),

ci i,..n >.ci i., coocyir, -i nao = ciuco.crr, + coa + caH5oi-i.

2.   Concentrated alcoholic potash decomposes the ester into
two molecules of acid (acid decomposition),

i:ii.,.co.cir,,.cooGjir, -i- 2ir.,o = CIL.COOII + CH,.COOH

'

If the alkyl derivatives of the ester arc employed, it is
possible to effect the synthesis of a scries of ketones and
saturated aliphatic acids, according to whether the one or other
reaction is used.

Of the other synthetic processes which have been studied in
connection with this substance, the following maybe mentioned :

i. The monoalkyl derivatives yield with nitrous acid the
isonitroso-dcrivative, from which the ortho-diketone may be
obtained (v. Pechmama),

ni.,.c<).c:ii(cn,,).cooG>iir, -i- UNO,,- CII.{.CO.C:(NOII).CH.>

+ 'GJIOOH + ii2o.

(MI;,C().C:(NOH).CII;{ -!~ II2O = CII.,.CO.CO.CII3 + NII2OII.

JJiacftyl.

These  compounds  readily condense,  forming   derivatives   of
quinonc,

()  i CO. C1I   II,,             CII,.C .CO . CII

!                                                "         =      ' I                                I    -

IToj.CO.C     O   .CII.,           CII.CO.CTLj

Dimetliyl (|ulnone.

ias and acetoacetic ester yield  pyricline

2. Aldehyde
derivatives (M

H

intxsch),

Nil

nil
o i

CII
CIL

II

Nil

crr,.c    ecu-.

C.CO.OC,H5

CoHr,O.CO.C
\/
CH
CHS
Dihydrocollidinedicarboxylic estsr.
PRACTICAL ORGANIC CHEMISTRY

3.   Orthoformic ester and acetoacetic  ester  in  presence of
acetic anhydride form a hydroxymethylene ester (Claisen),
CH,                                   CH3
I    "                                    I
CO                                     CO
Clio + HC(OOCJLj)8   = C:CH.OCol-L; + 2CoH->OH,
I    -                    "                |
COOC2II5                          COOCjIIg
4.  The derivatives of acetosuccinic ester are very numerous
the compound lending itself readily to the formation of hetero-
cydic compounds (pyrrole, furfurane, thiophene, pyridine, &c.,
derivatives).
The impartial way in which acetoacetic ester was found to
behave, sometimes playing the part of a hydroxy-compottnd,
sometimes that of a ketone, has led to much discussion on the
merits of the formulre proposed by Geuther and Frankland,
CIL.C(OH):CIJ.COOC2II5.           CII:>CO.CHo.COOC2liri.
Geuther's formula.                                Frankland's formula.
From its physical properties and from its close analogy with
compounds which are known in both dcsmotropic forms, there
is now little doubt that the liquid is a mixture of both com-
pounds, the proportion of each being determined by tempera-
ture and other conditions. It is a typical example of 1automcr~
ism.1
PREPARATIONS   17—18.
Monochloracetic Acid and Monobromacetic Acid. —
The action of chlorine on the aliphatic acids takes place in
presence of sunlight, also on the addition of small quantities of
the " halogen-carriers," iodine, sulphur, and red phosphorus. By
the action of iodine, I Cl is formed, which decomposes more readily
than the molecule of chlorine, and hydriodic acid is liberated,
CH8.COOH + IC1 = CHoCl.COOH + HI.
The hydriodic acid is then decomposed by chlorine, and IC1
regenerated. Phosphorus acts by forming the chloride of
phosphorus from which the acid chloride is produced, which is
more readily attacked by chlorine than the acid. Sulphur
behaves in a similar fashion, sulphur chloride converting the
l For a full discussion of the subject of tautomer!sm, see the author's Organic
Chemistry for Advanced Students, E. Arnold, London.
APPENDIX                                     253

acid into the acid chloride. Bromine in presence of phosphorus
forms in the same way, first, the acid bromide, and in the
second stage of the reaction, the bromine substitution product.
The bromine in all cases attaches itself to the a-carbon (z>.,
next the carboxyl). Where no free hydrogen exists in this
position, as in trimethylacetic acid, no substitution occurs.
Iodine can be introduced by the action of KI on the bromine
derivative,

CILjIJr.COOIl -I- KI = C1U.COOH + KBr.

Monohalogen derivatives may also be obtained from the
unsaturated acids by the action of the hydracids (HC1, HBr,
HI). In this case the halogen attaches itself to the carbon
farthest from the carboxyl. Thus acrylic acid gives with HBr
the /3-bromopropionic acid,

rilo-.CII.CO.OII   !   HI5r~CII.jlir.CILj.COOH.

The action of the hydracids, PClr, andPI3r5, on the hydroxy-
acids also yields the halogen derivatives,

riI:1.CI!(OiI).CO()II -I   HBr. = CILj.CIIBr.COOH + HaO.

au<:ii(<>ii).coon >i 2pci, = cn,.cnci.coci + 2?6ci,

-I-2I1C1.

In the latter case the acid chloride must be subsequently
decomposed by water to obtain the acid.

The increase in the number of halogen atoms in the acid
raises the boiling point as well as the strength of the acid as
determined by its dissociation constant K.

15.1'.                            K.

Act-tic ucid.......     118°           '0018

Monochlonvct'lie acid   .   .   .      185°           "155

Diclilorucctic ucid.....      190°         5*14

Trichloracctic ucid   ....      195°      121

Some of the transformations of monohalogen acids are
illustrated by the following equations :

CII.,n.<'<><)! I   t   II.jO          (.'ILjOH.COOII -i   I1CL

CILCl.COOIl   I   KCN    ~ CHyCN.COOII -I   K.C1
CIIoCl.C'OOII   !   2NH:,   •- CIIyNIUCOOlI   I   N1I4CL

£C'U.,Iir.C(.'K)II   I   Ag..      -=--•    |    "             + 2AgBr
CIIo.COOH
T  KOII - CII2":CI1.COOH + KI + H2O.


254

PRACTICAL ORGANIC CHEMISTRY

PREPARATIONS 19—20.

Glycocoll.—By the action of primary and secondary amines,
corresponding amino-acids are formed. Chloracetic acid and
methylamine yield sarcosine,

xCl                                 /NHCI-L

CH2           + NH3CH8 = CH2            + HC1.

\COOH                       \COOII

The   amino-acids   are   further   obtained   by  the   reduction
(Zn and HC1) of nitro-, oximino- and cyano-acids, thus :
CHo(N().2).COOII + 3Ha= CHa(NI Ia)COOII + 2li2O,
CH3.C(NOli).COOH + 2llo = CH3.C1I(NH.,).COOII + HaO9
CN.COOH -h 2lL = CHo(NII.2).c6oH,

and by the action of NH3 on the cyanhydrin of aldehydes and
ketones, or simply of ammonium cyanide. The product is then
hydrolysed with HC1,

/CN

/         NH3

/CN

CH3.CH

H.,0

/COOII

HCN
CH3.COH •>    CII3.CII

\>H              \Nl-Ia           \NII,

The amino-acids are crystalline compounds usually of a sweet
taste and soluble in water. They are neutral compounds, from
which it may be assumed that an inner ammonium salt is
formed—

/NH3

Nboo

By the action of an acid chloride on the amino-acid, the hydro-
gen of the amino-group may be replaced by an acicl  radical.
Hippuric acid has been synthesised in this way.
yNHo                            ,NH.CO.CGH5

CH2         + C6H5COC1 = Clio                 + IIC1   .

\coon                   XCOOH

The amino-acids are not acted on by a hot solution of caustic
alkali, but on fusion with caustic soda or potash, yield the
amine and CO,,,

/NH2

CH,.CH            - CIL.CH2.NH2

\COOH

CO2.
APPENDIX

With nitrous acid the hydroxy-acid is formed,
/NH,                          OH

CH.2            + HNOo = CHo

XCOOH

PREPARATION 21.

Diazoacetic Ester.—The primary amines of the aliphatic
scries differ from those of the aromatic group in the fact that the
former yield no diazo-compounds with nitrous acid. It is other-
wise with the ammo-esters, the ester group probably furnish-
ing the acid character (represented by the nucleus in the aromatic
series) necessary to give stability to the compound. It should
be pointed out that the two classes of compounds have not an
identical structure. The formation of diazoacetic ester from
pyruvic ester and hydrazine and subsequent oxidation with mer-
curic oxide indicates that both nitrogen atoms are attached to
carbon,

CM:i\                                     C1I3X      ,NH

>CO + NIL.NHo ->            \c/1        -^

CII.O. OX              •"       "        CH,O.C(X    \NH

-N

In addition to the reactions described in the preparation
diazoacetic ester unites with uiisaturated acids and forms cyclic
compounds. Fumaric ester, for example, combines in the
following way : —

>     RO.OCHC/V             ^

COOK            CII.COOR           RO.OC.HC— 'CH.COOR

RO.CO.CH

I    \               +   Na.

KO.CO.CM— CM.COOR  .

When bisdiazoacetic ester is heated with water or dilute acid
it  breaks up into hydrazine and oxalic acid,

/N=N\                                  COOH

HOOC.CH<         >CH.COOH + 4HoO = 2 |

\N=N/                        "        COOH


256               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 22—23.
Ethylmalonic Acid.—Like acetoacetic ester (see p. 83),
dlethylmalonate contains the group CO.CHo.CO. By the
action of sodium or sodium alcoholate, the hydrogen atoms of
the methylene group are successively replaceable by sodium.
The sodium atoms are in turn replaceable by alkyl or acyl
groups. Thus, in the present preparation, ethyl malonic ester
is obtained by the action of ethyl iodide on the monosodium
compound. If this substance be treated with a second mole-
cule of sodium alcoholate and a second molecule of alkyl iodide,
a second radical would be introduced, and a compound formed
of the general formula
X\
J>.C(C02C2H5),,
in which X and Y denote the same or different radicals.
These compounds yield, on hydrolysis, the free acids, which,
like all acids containing two carboxyl groups attached to the
same carbon atom, lose CO2 on heating. Thus, ethyl malonic
acid yields butyric acid. In this way the synthesis of mono-
basic acids may be readily effected. Malonic ester, moreover,
may be used in the preparation of cyclic compounds as well as
of tetrabasic and also dibasic acids of the malonic acid series
(Perkin). To give one illustration : malonic ester, and ethylene
bromide in presence of sodium alcoholate, yield trimethylene
dicarboxylic ester and tetramethylene tetracarboxylic ester. Th e
first reaction takes place in two steps,
CHNa(COOC3HB)2 + CaH4Br3 = CHoBr.CH.,CH(COOC2H5)2 + NaBr.
CHNa(COOC,H5)o + CEUBrCH., CH(COOCJL)
CH.,' "
= |    " >C(COOC,H5)o + NaBr + CH,(COOC,H5).,.
CH./
In the second step a second molecule of sodium malonic ester
exchanges its sodium -with the substituted malonic ester and a
second molecule of NaBr is then removed.
The formation of the tetracarboxylic ester occurs simultane-
ously,
2CHNa(COOCoH,)., + G,H4Br.,
= (COOCoH5).2CH. CH2. CH,. CH(COOCaH6)2 + 2NaBr
APPENDIX                                   257

The free acid derived from the ester by hydrolysis loses two
molecules of CCX on heating, and gives adipic acid,
(COOH).,CII.CiIo.ClIo.CII(C(X)ll),

= ajc)n.cu,.ciL,.cii,crL,cooH + 2co2.

Cyanacetic ester has similar properties to malonic ester, inas-
much as the mcthylcne hydrogen is replaceable by sodium and
thus by alkyl groups.

CN
	CN
	CN

I
	1
	|

rn.,          ->
	CI-INa            ->
	C1IX

1
	1
	1

COOCJIr,
	COOG,H5
	C00(

PREPARATION 24.
Trichloracetic Acid.—This acid may also be obtained by
direct substitution of acetic acid by chlorine (Dumas) (see Prep.
17, p. 87). The oxidation of the corresponding aldehyde is,
however, the more convenient method. Trichloracetic acid
decomposes with alkalis on heating into carbon dioxide and
chloroform,
CC1...COOIT =s CIIC13 H- CO,,.
The reaction resembles the formation of methane from sodium
acetate when heated with soda-lime.
On reduction with sodium or potassium amalgam, trichlor-
acetic acid is converted into acetic acid (Mclscns),
c:ci;,.(.:oon i- 311.5 = cn3.cooi-i + 3110.
Dichloracetic acid may also be obtained from chloral by the
action of potassium cyanide and water,
CCLjCOl!   |  IL.O -|- RON ^ CIIClo-COOII + KC1 + HCN.
Whereas mono-and tri-chloracetic acid are solid, dichloracetic
acid is a liquid at the ordinary temperature.
PREPARATION 25.
Oxalic Acid.—The preparation of oxalic acid by the action
of nitric acid on sugar was introduced by Schcele, and was used
for some lime as a technical process. The vanadium pent-
oxide acts as carrier of oxygen, being alternately reduced to
tetroxide and re-oxidised. The present commercial method is
to heat sawdust with a mixture of caustic potash and soda on
COHEN'S ADV. r. o. c.                                             s
258                PRACTICAL ORGANIC CHEMISTRY
iron plates to 200—220°, and to lixiviate the product with water.
The acid is precipitated as the calcium salt, which is then decom-
posed with sulphuric acid.
PREPARATION 27.
G-lyoxylic and Grly collie Acids.—The process of electro-
lytic reduction has been applied successfully to a large number
of organic compounds, and has not only been found to have
definite practical advantages in many cases over other methods,
but, on account of the ease with which it may be controlled, has
elucidated the various stages in the mechanism of some of the
more complex changes. The reduction of nitro-compounds is
illustrated in Preps. 49 and 50. The reduction of organic acids,
ketones and carbonyl compounds generally has been developed
by Tafel and others, and in these cases it is found advantageous
to use a mercury or lead electrode. An essential feature of the
process is a clean metallic surface at the cathode and the absence
of foreign metallic impurities. The redaction of the carbonyl
group proceeds in three steps :
V                       V
>CO + 2li = C(OII) - C(OH)
>CO + 2l-I = >CHOII
>CO + 4ll = >CH2 + H,CX
PREPARATION 28.
Palmitic Acid.—This acid, together with stearicand oleic
acids, in the form of the glycerides, are the chief constituents of
fats. Palmitin (glyceride of palmitic acid) is also found in
certain vegetable oils like palm and olive oil. The acid occurs
also as the cetyl ester in spermaceti and as the myricyl ester
in bees-wax. It may be obtained from oleic acid by fusion
with potash,
Q8HW03 + 50 + 5KOH = daH.aO.jK + 2K2COa +4ILO.
In the analysis of oils and fats, where the quantity of fatty acid
is the  chief object of the determination,  it  is customary  to
hydrolyse the substance with a standard, solution of alcoholic
potash in place of aqueous potash, and to estimate the excess
APPENDIX                                    259

of free alkali with standard acid, using phenolphthalein as
indicator. The difference gives the amount of alkali neutralised
by the fatty acid (see p. 210).
PREPARATION 29.
Formic Acid.—In addition to the method described, the
acid is formed in the decomposition of chloral (see p. 9),
chloroform (see Prep. 8, p. 71), by the action of cone. HC1 on
the isocyanicles,
C,H5NC + H20 = C,H5NHo + HCO.OH,
by the decomposition of aqueous hydrocyanic acid, which yields
the ammonium salt,
HCN + 2l-IaO = HCOONH4,
and by the oxidation of methyl alcohol with potassium bichrom-
ate and sulphuric acid. It is present in the sting of ants and
nettles, and is also occasionally found among the products of
bacterial fermentation of polyhydric alcohols and carbohydrates.
The commercial method is to act on solid NaOH with CO
under pressure and at a temperature of about 100° :
CO + NaOH = IICOONa.
The calcium salt is used in the preparation of aldehydes by
heating- it with the calcium salt of a higher aliphatic acid,
(HCOO)oCa -1- (CH3,COO)aCa = 2CH3CO.H + 2CaCO;;.
The reducing action of formic acid and' formates on metallic
salts may be ascribed to the presence of the aldehyde group
(OH)CH:O in the acid.
PREPARATION 30.
Allyl Alcohol.—Note the difference produced by the
change in the relative quantities of glycerol and oxalic acid,
and the temperature at which the reaction is brought about.
In the case of formic acid, it is the oxalic acid alone which
undergoes decomposition, and theoretically a small quantity of
glycerol will effect the decomposition of an unlimited amount
of oxalic acid. But at the higher temperature it is the glycerol
which yields the main product. Allyl alcohol being an un-
S 2
260               PRACTICAL ORGANIC CHEMISTRY
saturated compound, forms additive compounds with halogens
and halogen acids. With permanganate solution it may be
converted into glycerol,
CH2:CH.CHoOH + H\jO -\- O = CH2OH.CHOH.CH.jOH.
On oxidation with silver oxide it yields the corresponding alde-
hyde (acrolein) and the acid (acrylic acid).
PREPARATION  31
Isopropyl Iodide.—The replacement of hydroxyl by iodine
in the action of phosphorus and iodine on alcohols has already
been described (see Prep. 6, p. 68), but here the presence of an
excess of hydriodic acid, which is due to the action of water on
the phosphorus iodide,
PI8 -h 3H,0 = P(OH)3 + 3HI,
exerts in addition a reducing action on certain of the hydroxyl
groups. By diminishing the proportion of phosphorus and
iodine to glycerol, the reaction may be interrupted at an earlier
stage, when ally! iodide is formed. This is probably due to the
splitting off of iodine from propenyl tri-iodide,
CILJ.CIILCIU = CH2:CH.CH.J + I3,
On the other hand a larger proportion of phosphorus and iodine
or cone, hydriodic acid will reduce allyl iodide to propylene,
CII3:CM.CHaI -1- HI = CH2:CII.CH, + L,.
The action of hydriodic acid on glycerol is typical of the
polyhydric alcohols. Hydriodic acid converts erythritol into
secondary butyl iodide, and mannitol into secondary hexyl
iodide. The normal iodides are never formed.
PREPARATION  32.
Bpichlorhydrin.—It is a noteworthy fact that althoug-h
hydrochloric acid can replace hydroxyl by chlorine in the case
-of the monohydric alcohols, the number of hydroxyl groups wliich
are substituted in the case of polyhydric alcohols is strictly
limited. Like glycerol, ethylene glycol gives a chlorhydrin,
CHoOH.CHoOH -1- IIC1 = CH-oOH.CHoCl + I-IflO.
APPENDIX                                      261

1 The remaining- hydroxyls can always be replaced by chlorine
by the action of I'd... The chlorhyclrins may also be obtained
by the action of MOCl on the olcfines. It is a general property
of these compounds to form the oxide when heated with caustic
alkalis. Ethylenc chlorhydrin gives cthylene oxide in this way,

CUXl.CIL/lII + NaOII = GIL,. GIL, + NaCl + ILO.

O

Compounds like cthylene oxide and epichlorhydrin may be
regarded as inner ethers,

/GIL,                       /CH,

o<|  -               o/    3

XCH2                      \CH3

TCthylene oxide.                     Dimethyl ether.

These oxide:; are easily decomposed. With water, ethylene oxide
forms glycol ; with hydrochloric acid, the chlorhydrin ; with hydro-
cyanic acid, the cyanhydrin. PZpichlorhydrin behaves similarly.

PREPARATION  33.
Succillic Acid. — Tartaric acid, like malic acid, is converted
into succinic acid on reduction with HI, and the relationship of
these three acids is thereby established. The constitution of
succinic acid itself has been determined by its synthesis from
ethyienc (Maxwell Simpson). Ethylene unites with bromine,
forming ethyienc bromide, which yields ethylene cyanide with
potassium cyanide. The latter is then bydrolysecl.
CM,          ClUir          CII,CN          CHo.COOH
CH,   "^   CIU5r    "^    CIIgCN    "^    CII2.COOH
it is an interesting fact, not yet fully explained, that the
alkyl succinic acids give anhydrides more readily than succinic
acid, and the greater the number of alkyl groups, the more
readily is the anhydride produced. Thus the anhydride of
tetramethyl succinic acid is so stable that it is not decomposed
by water.
The symmetrical dialkyl succinic acids exist in two forms,
each yielding a separate anhydride. From their similarity to
i

!

262                PRACTICAL ORGANIC CHTO'MISTRY

the anhydrides of hexahydrophthalicacid, they are distinguished
as cis- and trans-compounds (see Notes on Prep. 37, p. 265).

CH,
NCH.CO                       HoC'      CH.CO

Clio

/\

CH.CO
CH.

Dimethylsuccinic
anhydride.

HoC

CH.CO

O

CH2

Hexahydrophthalic
anhydride.

PREPARATION 34.

Ethyl Tartrata—The speculations of Pasteur (1860) on the
cause of the optical activity and hemihedry of tartaric acid and
its salts, and of Wislicenus (1873) on the existence of three
lactic acids, have developed in the hands of Van't rioff and
Le Bel (1874) into the present theory of stereo-chemistry or
atomic space arrangement. Optical activity is found to be in-
variably associated with the presence in the substance of an
asymmetri.-:. carbon atom, i.e. one linked to four different groups.
Now every asymmetric (unsymmetrical) object like a hand or
foot has its fellow ; but the two do not precisely overlap, and
every substance containing an asymmetric carbon atom, round
which the four groups are distributed, not, as usually repre-
sented, in one plane, but in space of three dimensions, is
capable of existing in two forms, which correspond to a left and
right hand, or to an object and its reflected image.

This is represented by making- the carbon atom the centre ot
a tetrahedron and attaching the four different groups to the

four solid angles.    The two forms will then appear as in the
Fig., in which ABCD represent four different groups.   When
AIM'KNDIX                                           26-2

using actual models, it will he found that they cannot be turned
so as to coincide until two of the groups in one model have been
interchanged.

The main difference between two such substances lies in their
action on polarised light, the one turning it to the right (dextro-
rotatory) and the other to the left (lacvo-rotatory), when in the
liquid or dissolved state. Although every optically active sub-
stance contains at least one asymmetric carbon atom like amyl
alcohol and malic acid, or two like tartaric acid (the asymmetric
carbon is represented in heavy type),


	
	11

I'll.
	ClUCOOH
	1

1
	1
	no— C--COOH

0    II
	no - c ....... ii
	i

1
	1
	no-c— coon

CILOII
	coon
	1


	
	IF

aitiyl alcohol.
	Malic acid.
	Tnrtaric acid.

the converse does not always hold ; for there arc many com-
pounds which possess an asymmetric carbon atom and show no
rotation. The cause of this may be, either that the substance is
a. mixture of equal quantities of the two forms, which by having
opposite rotations neutralise each other's effect as in the case of
racemic acid, which consists of equal quantities of dcxtro- and
laevo-tartaric acid and produces what is termed "external com-
pensation,35 or the two similar asymmetric carbon atoms exist
within the same molecule and neutralise each other's effect by
"internal compensation," as in the case of mesotartaric acid.
External compensation is generally exhibited by artificially
prepared compounds as distinguished from natural products.
Thus, glyceric acid from glycerol is inactive, though it contains
an asymmetric carbon atom,

because it consists of a mixture of dcxtro- and lacvo-glyceric
acid in equal quantities, whereas tartaric acid, which occurs in
grapes, malic acid, which is obtained from mountain ash berries,
and also the sugars, terpenes, alkaloids, and a number of other
2&4              PRACTICAL ORGANIC CHEMISTRY

_ -                            - ............. -        — -

natural products are all active. One of the great achievements
of Pasteur in this line of research was the separation of inactive
"externally compensated" compounds into their active com-
ponents or "optical antipodes" or " enantiomorphs." One
method of separation is described in Prep. 35. For details of
other methods a book on stereo-chemistry must be consulted.

On the formation of ethyl tartrate, see notes on Prep. 15, p 247.
Ethyl tartrate may also be obtained by the method described
in Prep. 86, which rather curtails the operation and does not
necessitate the use of more than half the quantity of ethyl
alcohol required by the earlier process.

PREPARATION 35.

Racemic and Mesotartaric Acids.— These two acids
represent two inactive types of compounds containing' asymmetric
carbon atoms (see above). Apart from certain well-marked
differences in physical properties they also differ in one
important feature ; racemic acid can be resolved into its optical
enantiomorphs, whereas mesotartaric acid cannot. The latter
belongs to what is termed the inactive indivisible type. If we
examine the structural formula of tartaric acid it will be seen
that it possesses two asymmetric carbon atoms, denoted in the
formula by thick type.

H

HO— C— COOH
HO— C— COOH

.
J                           Each asymmetric carbon atom is attached to similar groups.
r| '                      Let us suppose that each asymmetric carbon with its associated
fl I                   groups produces a certain rotation in a given direction.    We
*j j                        may imagine the following combinations of two similarasyrnmetrie
||! {                       groups.    Both produce dextro-rotation, or both produce laevo-ro-
| j                        tation. They will represent the dextro andlaevoenantiomorphs,ancl
fyj                       the mixture of the two will produce inactive racemic acid. Racemic
I li                       acid is said to be inactive by external compensation.    Suppose,
|l|                       finally,  that the two asymmetric groups produce  rotation   in
I j                        opposite directions.     They will neutralise one another.    The
APPENDIX

265

resulting compound will be inactive by internal compensation.
Such a compound cannot be resolved by any process into its
active components. The above compounds may be represented
by the following projection formula?, in which the groups must-
be assumed to occupy three-dimensional space (the asymmetric
carbon atoms being denoted by cross-lines),

1

on
	:ooii
 i r
	coon n- ........ -on

U~
	—OH
	on — n

roon
 (/. Tartarit: acid.
		coon
 /. Tartaric acid.

coon
H—I—o

n—

—OH

COOH
Raccinic :\r'u\.                                       Mcsotartnric acid.
The conversion of active tartaric acid into the inactive forms
is known as raw what ion, and according to Winther is effected
by the interchange of the gnuips round each asymmetric carbon
atom successively so that part of the active acid is first con-
verted into mesotartaric acid, which then passes into the laevo
variety,
PREPARATION 37.
Citraconic and Mesaconio Acid.—The theory of Le Bel
and Van't IIoff has been extended to unsaturated compounds
like fumaric and maleic and the above two acids, which form
isomeric pairs. These two pairs of acids bear a close resemblance.
It has already been observed in the course of the preparation
that citraconic is readily converted into mcsaconic acid. More-
over, they both yield pyrotartnricacid, on reduction, but only one,
citraconic acid, forms an anhydride. Maleic acid in the same
way is easily converted into fumaric acid by bromine, both
maleic and fumaric acid yield succinic acid on reduction, but
only maleic acid forms an anhydride. The explanation is as
follows : in each pair of compounds there exists two carbon
atoms linked to one another by a double bond and each attached
to two different groups. Van't HofF refers the isomerism of each
pair to a space arrangement, which may be represented by
supposing two tetrahedra to be joined by a common edge.
As the centre of each tetrahedron is occupied by a carbon atom,
265

PRACTICAL ORGANIC CHEMISTRY

and the four bonds are directed towards the four corners of
the tetrahedron, this space arrangement will correspond to a
doubly-linked carbon. If the two spare corners of each tetra-
hedron are now occupied by different groups, it is possible to

produce two forms by transposing one pair of groups. Suppos-
ing A and H to represent two different groups, the above forms
will result

The two pairs of acids will be represented as follows :—

HO-CO

O-OH

CO'OH

O'OH

Fumaric acid.

Maleic acid.

CO'OH

O-OH

Mesaconic acid.

Citrac

Isomerism in this case is not characterised by optical activity,
as the groups lie in one plane and no structural asymmetry is
possible ; but is exhibited by such physical differences as solu-
bility, melting-point, electrical conductivity, and by the fact that
in the case of dibasic acids only one of the pair yields an anhy-
dride. Maleic and citraconic acid form anhydrides, but fumaric
and mesaconic acid do not. In the case of the acids which form
anhydrides, the carboxyl groups are supposed to be nearer
together, i.e. on the same side (as) of the molecule, in the other
case on opposite sides (trans] of the molecule. Maleic and
citraconic are "cis" acids, fumaric and mesaconic are "trans"
APPENDIX

acids. The following table gives the various physical proper-
tics, solubility, melting-point, and dissociation constant K of the
tu'o pairs of acids.

Mnleie . .
I''um;iric ,
Citniconic
Mesucnnic

s.
	M.l>.
	K.

very soluble
	130°
	1*17

much less soluble, very soluble, much less soluble.
	sublimes at 200° 80°
 202°
	•093
 '340 •079

Urea. —In addition to the method described in the prepara-
tion, urea may be obtained by the oxidation of anhydrous
potassium ferrocyanidc with potassium bichromate (Williams),
or manganese dioxide at a red heat, or by the action of per-
manganate on a cold solution of potassium cyanide (Volhard).
It has been synthesised by the action of ammonia on (i) phos-
gene, (.i) urclhane, (3) cbloroformic ester, and (4) ethyl carbonate.

NII,

1.                    COO, i 4NII.,-- NIIjj.CO.NIIo I 2NIJ4C1.

2.     Niucoor.,!!,, i

^.       ('1C(K)('„! Ir, I  3

4.        CO(()(!.,! hj., |  2

NIUCO.NIIo -f C,Ilr/)II.
NIUCO.NIIo H- CJIf.OH I NII4C1
NIUCO.NIIo -I- 2CoHrjOII.
also (5) by'the action   of dilute acid on cyanamidc, and (6) by
heating guanidine with dilute sulphuric acid or baryta.
S.               CNNIL I-  11,0 - NIUCO.N1U
(>.        Nil :C(NIL,).2 i   II..O ~ NIIo.CO.NIIa -!• NH3.
The synthesis of urea by Wohler in 1828 is usually regarded
as a. tiu:ning-point in tin; history of organic chemistry, when
organic compounds ceased to be merely products of a vital force,
associated with living animals and plants. They now assumed
for the first time an independent role as substances capable of
synthesis by ordinary chemical means. In point of fact this is
not strictly true, for Scheele had prepared oxalic acid, only
previously known in wood sorrel and other plants, from cane
sugar, and Dobereincr had obtained the formic acid of ants by
the oxidation of tartaric acid. The formation of urea offers an
interesting example of intramolecular change of which many
cases are now known. See the formation of benzictine from
268

PRACTICAL ORGANIC CHEMISTRY

hydrazobenzene (Prep. 51, p.  148) and aminoazobenzene from
diazoaminobenzene (Prep. 70, p. 172),

PREPARATION 39,

Thiooarbamide.—This is an example of a reversible
reaction, in which either ammonium-thiocyanate or thiourea
when heated yields the same equilibrium mixture. It may he
shown by melting a little thiourea for a minute, when the
presence of thiocyanate is indicated by the addition, of FeCLt.

PREPARATION 41.

Alloxan.—The decomposition of uric acid into alloxan and
area renders the constitution of alloxan of value in elucidating
the structure of uric acid. The constitution is derived from the
following facts : Alloxan is decomposed with caustic soda or
potash into mesoxalic acid and urea, and with hydroxylamine it
combines to form violuric acid, which points to the presence of
a ketone group (Baeyer). Barbituric acid and nitrous acid
also give violuric acid, and seeing that barbituric acid has
been synthesised from malonic acid and urea by the action of
phosphorus oxychloride (Grimaux), it is unquestionably malonyl
urea. The relationship of these substances must therefore be
represented as follows :

NH—CO            NH-CO

CO    CO

I         1
NH—CO

Alloxan.

CO     C:NOH

I         I

NH—CO

Violuric acid.

NH—CO

CO     Clio
I          I

NH—CO

Barbituric acid.

A. renewed interest attaches to alloxan since E. Fischer's dis-
covery of the new synthesis of uric acid. The steps in the
synthesis are briefly the following. Alloxan and ammonium
sulphite form thionuric acid, which is decomposed by hydro-
chloric or sulphuric acid into uramil.

NH—CO                        NH—CO

I         I /NH2                 |         |

:o  ->    co   c(          ->    co   CH.NH.,

II        II XSO,H        |         |

NH—CO            NH-CO                        NH—CO

Alloxan.                 Thionuric acid.                         Uramil.

Nil—CO
CO     0

ll
APPENDIX                                  269

Uramil and potassium cyanate unite to form potassium pseudo-
urate,

NH-CO                             Nil—CO

II                 I     I

CO CIINH.-fOCNK =   CO CH.NH.CO.NHK.

II          II

NH—CO                              NH—CO

Potassium pseudourate.

When free pseudouric acid is heated with 20 per cent, hydro-
chloric acid it yields uric acid,

NH-CO                           NH—CO

II         II

CO     CH.NH.CO.NH2   = CO '   C—NIL

II                       I         ||           >CO + HoO.

NH—CO                            NH—C—NH/

Pseudouric acid.                                   Uric acid.

Other synthetic methods are also known for which a book of
reference must be consulted.

PREPARATION 42.

Caffeine. — The close relationship existing between uric acid
and caffeine has long suggested the possibility of converting uric
acid, a comparatively plentiful material, into caffeine, an important
and costly drug, occurring only in small quantities in tea and
coffee. The problem has been solved by E. Fischer, who has
succeeded in synthesising caffeine in a variety of ways. Fischer
found that by using the same series of processes as described
above in the synthesis of uric acid, but substituting dimethyl-
alloxan for alloxan, and methylamine sulphite for ammonium
sulphite, trimethyl uric acid is formed, and is identical with
hydroxycaffeine,

CH3N -- CO

I         I

CO    C-N(CH3)

I         /C°     "

CH3N - C— NH

Tritnethyl uric acid (Hydroxycaffeine).

Hydroxycaffeine is converted into caffeine by acting upon  i
with a mixture of phosphorus pentachloride and oxychloride.

it                   J
I
270

PRACTICAL ORGANIC CHEMISTRY

This forms chlorocaffeine, which is then reduced with hydriodic
acid to caffeine,

CH..N-----CO

"\                           \

CO     C-

-N(CH3)
)CQ  J

-N

CH3N-----CO

CO     C—N(CH3)

Chlorocaffeine.

Caffeine.

The same result may be obtained in a simpler way by
nethylating uric acid, and converting it into trimethyluric acid
and then into caffeine ; or by preparing the mono- and cli-mcthyl
derivatives of uric acid, reducing these to the corresponding
mono- and di-methylxanthines and introducing additional
methyl groups into the product.

PREPARATION 44.

Tyrosine, Leucine.—It has long been known that mineral
acids and alkalis possess the property of breaking up albuminoid
substances and resolving them into the simpler ami no-acids.
The recent introduction by Fischer of a method of separating
the amino-acids by converting them into volatile esters followed
by fractional distillation in vacuo has led to the recognition of the
wide distribution of such acids as alanine, serine, and phcnyl-
alanine, and to the discovery of two cyclic acids, pyrrol idine-
carboxylic acid and hydroxypyrrolidine carboxylic acid. The
following is a list of amino-acids from albuminoid substances
which have been separated by fractional distillation of their
esters under reduced pressure :

Ethyl ester.
	b.p.
	Pressure in rnm.

Glycocoll   .   ,          .
	tl 'p — CO'C0
	Tn

Alanine      ....... Aminoisovaleric acid   . Leucine     ....... Aspartic acid
	JL j    j~ :>
 48'50 63"50
 S;r5u 126-5°
	10
 8
 12
 1 1

Glutamic acid   ..... Phenylalanine   .....
	139 — 140° 143°
	IO 10

APPENDIX                                    27I
PREPARATION 45.
Grape-sugar.—Although grape-sugar yields neither a bi-
sulphite compound nor gives Scruffs reaction under ordinary
conditions, its properties are for the most part those of an
aldehyde. In addition to its reducing action on copper and
silver salts, and its combination with phenylhydrazine, it forms
an oxime with hydroxylamine and a cyanhydrin with hydro-
cyanic acid. On reduction it gives the hexahydric alcohol
sorbitol, and, on oxidation, the corresponding monobasic acid,
gluconic acid, and the dibasic acid, saccharic acid,
C1L,OII(CIIOII)4COOH.          COOH(CHOH)4COOH.
Gluconic acid.                                   Saccharic acid.
The presence of five hydroxyl groups in glucose is determined
by the existence of a pentacetyl derivative. These and other
facts, which cannot be discussed in detail, have led to the adop-
tion of the present formula. The discovery of the optical
antipode of grape-sugar (which is dextro-rotatory) has deter-
mined the present name of dextro-glucose to distinguish it from
laevo-glucose, which is laevo-rotatory. For the synthesis of
these two sugars and the other mono-saccharoses, a text-book
must be consulted.
The other common sugars, which reduce alkaline copper
sulphate, arc fructose (laevulose), galactose, maltose and milk-
sugar, the two latter being disaccharoses. They are most
readily identified by the microscopic appearance and melting-
point of their phenylosazones. Cane-sugar is readily dis-
tinguished from the majority of the common sugars by its
indifference towards alkaline copper sulphate, until previously
boiled with a few drops of dilute sulphuric acid. It is then
inverted and gives the reactions for glucose and fructose.
PREPARATION 46.
Bromobenzene. -The replacement of hydrogen by the
halogens Cl and 13r, in the nucleus of aromatic hydrocarbons, is
assisted by the presence of a " halogen carrier," the action of
which has been referred to in the Note on the preparations of
chlor- and brom-acctic acids, p. 252. Iodine, iron, iron and
aluminium chlorides and bromides, the aluminium-mercury
];f»                    272                PRACTICAL ORGANIC CHEMISTRY

couple, and pyridine all behave in this way. The action of
iodine has already been explained on p. 252. Iron and its salts
are supposed to act by alternately passing from the ferrous to
the ferric state, the ferric salt delivering up its halogen in the
nascent state,

2FeBr2 + Br2 = 2FeBr3.
FeBr3 = FeBr2 + Br.

The action of aluminium and its compounds is not fully under-
stood. Pyridine probably acts by the intermediate formation of
the perbromide, as explained.

Unless a large excess of the hydrocarbon is present, the
action of the halogen will effect the substitution of a second
atom of hyrogen. By increasing the proportion of halogen,
all the hydrogen may be ultimately replaced by chlorine or
bromine. The second halogen atom enters the ortho- and para-
1 t ( :                   positions, never the meta. Another kind of compound is

obtained if the halogen is allowed to act in presence of sun-
light. In the 'case of benzene, the additive compounds, benzene
hexachloride and hexabromide, are then formed. They are very
unstable compounds, and readily give off hydrochloric and
hydrobromic acid. If boiled with alcoholic potash they are de-
composed, forming trichloro- and tribromo-benzene,

' l i                                 C6H6C16 + sKOH = CBH3C13 + sKCl + 3lIX>.

If chlorine and bromine are allowed to act upon an aromatic
hydrocarbon like toluene, which has a side-chain, substitution
may occur in the nucleus or the side-chain, according to the
conditions. Generally speaking, in the cold and in presence of
a "halogen carrier," nuclear substitution occurs, but at a high
temperature the halogen passes into the side-chain (see Prep.
86, p. £94).

,                 .         The halogen derivatives of the aromatic hydrocarbons, like

those of the aliphatic series, are colourless liquids or soli els,
denser than water, and possessing an agreeable smell, unless
the side-chain is substituted. The latter substances can often
be distinguished by their irritating action on the eyes and mucous
membrane of the nose (see Prep. 86, p. 194).
I1 1                             The halogen in the aromatic nucleus is much more firmly

fixed than in the case of the aliphatic compounds, e.g. bromo-
benzene is quite unaffected by most of the reagents which .act


APPENDIX                                     273

upon ethyl bromide. The presence of 7W//-0- groups, however,
disturbs this stability, and the halogen in a substance like
dinitrochloroben/ene is readily replaced by hydroxyl with
potash, or by N II., with ammonia. When the halogen is in the
side-chain, the substance behaves like an aliphatic compound.

PREPARATION  47.
Ethyl Benzene.--—" Fittig's reaction," so-called from its
discoverer, is analogous to the synthetical method employed by
Wurt/. for the preparation of the aliphatic hydrocarbons, as in
the formation of butane from ethyl bromide^
2( U Ir,I5r -I- 2Nn = Cy 1 10 -I- 2NaBr.
In the case of the aromatic hydrocarbons, a second side-
chain may be introduced from ,-r dibrornodefivative cither
simultaneously with the first, or subsequently by a repetition of
the process. Both dibromobenzcne and monobromotolucnc
may be converted into xylene.
t.y I4I{r.j -I- 2(:n,I   ! 4N;i .-..- QlI^CIIj^ + 2Na«r H- 2'NaI.
Crtn.iHr(;H:,   -I-   CH.J   I  2Na :.-- (Y,II4(CII,,),s -I- Nul -I- Na'Bn
The action  also takes  place between aromatic  hydrocarbons
substituted either in the nucleus or side-chain.     Urumobenzcne
yields diphenyl, wliereas benxyl bromide yields dibenzyl,
2Cfi!I6I{r I- 2Na .- CflIIft.CVtB -I- 2NaIk.
2Q;I I5CI I,Hr f 2Na ^ C(i! Ifl.CIta.Clla.C,jir5 ~f aNaBr.
This reaction does not, however, occur with the same readiness
in all cases, nor does it always yield exclusively the anticipated
product. Para-broinotoluene and sodium give tolyl phenyl
methane and diben/.yl as well as ditolyl (Wciler). Again, p-
broniololuene gives a good yield of /-xylenc, the ortho-compound
reacts sluggishly, whilst the meta-derivative gives no xylene.
O<x:asionally the action is vigorous, and has to be moderated by
dilution with an indifferent solvent. At other times it is sluggish
and has to be promoted by raising' the temperature. Often the
addition of a little ethyl acetate will start the decomposition.
For the synthesis of ;;omc of the aromatic hydrocarbons, it is
preferable to 'use the Friedel-Crafts' reaction (see Prep. 102,
]>• 214).
COHEN'S ADV. p. o. c.                                                  T
274               PRACTICAL ORGANIC CHEMISTRY

PREPARATION  48
Nitrobenzene.—The formation of nitro-compounds, by the
action of strong nitric acid on the hydrocarbon, is a distinctive
property of aromatic compounds, although recent researches
have shown that dilute nitric acid under pressure will convert
some of the paraffins, especially the tertiary hydrocarbons, into
mono- and cli-nitro-derivatives. The production of nitro-com-
pounds is usually effected by strong or fuming nitric acid, or
solid potassium nitrate, in presence of cone, sulphuric acid.
Where the action is vigorous, as in the case of the phenols, it
is necessary to use moderately dilute acid. The number of
hydrogen atoms replaceable by the nitro-group (N02) is limited.
In benzene the first nitro-group is introduced with great ease,
the second less readily, and the third with some difficulty. The
position taken up by the nitro-groups may be briefly stated as
follows : When a negative group (nitro, carboxyl, cyanogen,
aldehyde) is already present, the nitro-group enters the meta-
position to the first group. In the presence of other groups
(alkyl, hydroxyl, halogen, ammo), the nitro-group attaches itself
to both ortho- and para-positions. Benzoic acid and benz-
aldehyde give, on nitration., mainly meta-compounds, whereas
toluene, phenol, and aniline form simultaneously ortho- and
para-derivatives.
Nitro-compounds have often a yellow or red colour, are with
difficulty or not at all volatile, possess a much higher boiling-
point than the corresponding halogen derivatives, and are
denser than water, and insoluble in that liquid.
PREPARATIONS 49—51.
Azoxybenzene,   Azobenzene,    Hydrazobenzene.—-
Nitro-compounds yield a series of reduction products accordingto
the nature of the reducing agent. Alkaline reducing agents :
sodium methylate, zinc dust and caustic soda, stannous chloride
and caustic soda, produce azoxy, azo- and hydrazo-compounds.
C6H5N02          C6H5N.                C6H5N           C6H5NII
I >0              ||               |
C6H8N02          C6H5N/               C6H3N           C(5H5NH
Nitrobenzene.         Azoxybenzene.          Azobenzene.        Hydrazobenzene.
The sodium methylate acts as a reducing agent by taking up
oxygen and forming sodium formate.
APPENDIX

275

V

«+

in the preparations, the nitrobenzene is converted by suc-
cessive steps^ into azoxy-, azo- and hydrazo-benzene ; but, by
suitably modifying the conditions, the intermediate steps may
be omitted. Thus, nitrobenzene may be converted with alcoholic
caustic soda and zinc dust directly into hydrazobenzene.
If the  reduction  of   nitrobenzene  takes place   in   neutral
solution with zinc dust and water in presence of a little calcium
or ammonium chloride, or with aluminium-mercury couple and
water, /^-phenylhydroxylamine is formed (see Prep. 52, p. 148).
C0II5NO2 + 2H3 = C6H5NIIOH + HoO.
Reduction in acid solution produces an amine (see Prep. 53,
p. 149). The mechanism of the change, although giving rise to
such different products when carried out in alkaline, neutral, or
acid solution, is not essentially different in the three cases. The
first reduction product is nitrosobenzene, CGH5NO, followed by
that of p-pheriylhydroxylamine. In alkaline, solution the two
compounds unite with elimination of water to form azoxybenzene,
which may undergo further reduction in a normal fashion giving
rise to azo- and hydrazo-benzene. In acid solution, on the
other hand, p.henylhydroxylamine does not combine with nitroso-
benzene and can then undergo further reduction. The reduction
of nitrobenzene in alkaline and neutral solution is also effected,
as already described, by electrolysing the liquid in contact with
the negative electrode. If the process is conducted in presence
of concentrated sulphuric acid /-aminophenol is obtained
(Gattermann). The latter is produced by intramolecular change
from phcnylhydroxylamine, which is first formed,
C6H0NHOH = OIICGH4NH.2.    '
Azobenzene, though not a colouring matter, may be regarded
as the mother substance of the large family of azo-colours,
which are, however, prepared by a totally distinct method, viz.,
by the action of a diazo-salt on a phenol or base (see Prep. 62,
p. 163). The intramolecular change from hydrazobenzene to
benzidine is one of great technical importance. The change
occurs by the transfer of the link between the two nitrogen
atoms to the two carbon atoms in the/^nz-position,
M Vi

276                PRACTICAL ORGANIC CHEMISTRY

If one of the nuclei of hydrazobenzene is already substituted
in the/rtnz-position, the reaction may give rise todiphenylamine
derivatives, which are known as ortho- or para-semidines
(Jacobson),
>NII-:    x_/
^                         NIL
^>—NH—/     NNIL     x/     X)-NII-<^     N
j                                                   Para-semidine.                                             Orlho-semidme.
|,                          Benzidine and its homologues are used in the manufacture of
11..                    valuable azo-colours, congo-red^ bcnsopurpurin, &c. (seep. 291).
<V '                                                   PREPARATION 52.
ff
\^                       Phenylhydroxylamine.—The   necessity for   conducting
{,,   |                      the   reduction   of nitrobenzene   in   neutral   solution  has  been
,Lj 5                        explained in the  previous note.    In  addition   to  the  reagent
'j'i                          named in the preparation,  the aluminium-mercury couple   in
^ ff                      presence of water or ammonium sulphide in alcoholic solution
^?|                      may   be   also   used.    The   conversion   of   nitrobenzene   into
;S*f                      ^-aminophenol  on  electrolysis   in  acid  solution  will  also   be
evident from the fact that phenylhydroxylamine readily under-
goes isomeric change. Phenylhydroxylamine reacts with
nitrous acid, forming a nitroso-derivative,
CflH3NHOH + UNO., = CBH0N(NO)OH -f-II,O.
It also condenses with aldehydes irf the following way :
C6H5NHOII -f CBHBCHO = CBTI5N—CILQIlB.
O
Nitrosobenzene, which shares the general character of nitroso-
compounds in giving rise to a green vapour or solution, is
readily reduced to phenylhydroxylamine and aniline. It
condenses with ammo-compounds, yielding azo- or diazo-
derivatives.
C6H,NO + H2N.C(5H, = CBH5N = N.C,irfi -I- IIaO.
C6H5NO + H2N.OIi   = C61I0N = N.OH + H2O.
APPENDIX                                    277

PREPARATION 53.
Aniline.—The reduction of a nitro-compound in an acid
solution is a very general method for preparing primary amines.
For laboratory purposes it is customary to use tin and hydro-
chloric or a solution of stannous chloride crystals (SnCl.>-h2*H.,O)
in cone, hydrochloric acid or zinc dust and acetic acid. The
manufacture of aniline on the industrial scale is effected by
means of iron borings and hydrochloric acid ; but of the latter
only a fraction of the theoretical quantity, required by the
equation Fe 4- 2HC1 = FeCL, -f H2, is employed. The main
reaction is probably represented by the following equation,
CJ I5N(X + 2Fe + 4H.20 = C6H5NIL2 + Pea(OH)6.
When the base is volatile in steam, as in the present case,
the simplest method of separation is to add an excess of alkali
and to distil in steam. Otherwise the base maybe separated
by shaking out with ether, or the tin may be precipitated in the
warm solution by H3S and the filtrate evaporated to dryness.
If the compound contains more than one nitro-group, the
reduction is carried out with one of the above reducing agents
in the manner described, but if it is necessary to reduce only
one of the nitre-groups, it is effected by the action of H2S in
presence of ammonia (see Prep. 58, p. 154). Another method,
which may also be used for determining the number of
nitro-groups, is to prepare an alcoholic solution of the nitro-
compound, and to add an alcoholic solution of the calculated
quantity of stannous chloride. In this way the reduction of the
groups may be carried out in succession and estimated.
The aromatic amines are colourless liquids or solids, which
may be distilled without decomposition. Although they form
salts with acids, they are much weaker bases than the aliphatic
amines owing to the negative character of the phenyl group.
The salts have an acid reaction to litmus, whilst the free bases
are neutral. The neutralisation of an aromatic base by acid is
usually determined by the use of methyl violet, magenta, or
congo-red paper. The first is turned green, the second colour-
less, and the third blue by free acid.
Aromatic amines, containing the amino-group in the side-
chain, have the basic character and properties of aliphatic
arrfines.
278                PRACTICAL ORGANIC CHEMISTRY

PREPARATIONS 54—55.

Acetanilide, Bromacetanilide.--Primary and second-
ary bases form -acetyl derivatives with acetic acid, acetyl
chloride, or acetic anhydride (see Reactions, pp. 76, 77)-
Tertiary bases are unacted on in this way. As the acetyl
derivatives are much less volatile than the original bases, the
method is frequently used for separating a tertiary base from
mixtures containing the other two (see Prep. 59, p, 156). The
anilides are very stable compounds ; they can be distilled, as a.
rule, without decomposition, and may be directly brominatecl,
chlorinated and nitrated. In these reactions, either the ortho-
or para- or both derivatives are formed. The remaining
hydrogen atom of the amino-group may be replaced by ( 0 a
second acid radical, by the action of acetic anhydride, (2)
sodium, by the action of the metal, (3) a nitroso-group, with
nitrous acid, and (4) chlorine or bromine, by the action of hypo-
chlorous or hypobromous acid.

CfiH5N(CO. CH,).2          Diacetanilide.

QjHsNNa. CO. Clio,         Sodium acetanilide.

C6H5N(NO)CO.CH,      Nitrosoacetanilide.

C(5H5NC1. CO.CH3         Acetchloranilide.

The mechanism of the change effected in producing substitu-
tion products by halogens appears to occur in two steps, the first
being the addition of a molecule of halogen, probably to the
nitrogen, the second being an isomeric change accompanied (if
water is present) by the elimination of halogen acid.

CflI-I5.NH.CaI-I3O 4- Br2 = C(;H5NILC2H,O

Br    Br
CGH;,NHBr.,.C2ILO = CGn4BrNH.CoIl>O.IIBr.
All the anilides are hydrolysed by strong mineral acids  or
alkalis and  the  acid radical  removed  (see  also  Beckniann's
reaction, Prep. loo, p. 212).
Formanilideis ^.taittomeric compound, z>., it reacts as though
it possessed the alternative formula:,
C6HSN:CI-I(OH)              C6H5NH.CO.H,
for it yields two isomeric ethers, the one,'by the action of
methyl iodide on the silver salt, and the other by the action of
methyl iodide on the sodium compound (Comstock). Acet-
APPENDIX

279

unilide is known in pharmacy as antifebrin, and is used as an
antipyretic.
PRKI'ARATIONS 57—58.
ni-Dinitrobenzene. In the Notes on Prep. 48, p. 274,
it is mentioned that the second nitro-group enters the meta-
position to the first. This is usually the case where two
acid groups arc successively introduced into the hydrocarbon.
Thus, ben/enedisulphonic acid, obtained by heating benzene
sulphonic acid (see Prep. 74, p. 177) with fuming sulphuric acid,
is a meta-compound.
m-Nitraiiiline.—The reduction product of w-dinitrobenz-
ene is naturally ///-nitranilinc. The o- and /-nitranilines can
be obtained by acting upon aniline or, preferably, acetanilide,
with fuming nitric acid.
Whereas the first nitro-group of a tri- or di-nitro derivatives is
rapidly and completely reduced by ammonium sulphide, the
second is very slowly attacked. The rate of change appears to
he determincd mainly by the acidic nature of the molecule as a
whole, the halogens and carboxyl playing a similar role to that of
the nitro-group. In all these cases hydroxylamine compounds
are produced as intermediate products.
PREPARATION 59.
Dimethylamline.-......It is a well-known Yfact that the alkyl
halidcs convert the primary amines into secondary and tertiary
bases (Ilofmann). The formation of dimethylaniline is prob-
ably due to the action of CH;1C1, which is formed, as an
intermediate product, by the action of hydrochloric acid on the
methyl alcohol. There is always a small quantity of mono-
methylaniline, C,.Hf>NIICH:l, produced at the same time. The
three bases cannot well be separated by fractional distillation,
as their boiling points lie too near together,
Aniline      ..........180°.
Mi'lhyliinilinc........192°.
Dimothyliinilinc.......I92°-
It is for this reason that the action of acetic anhydride is
utilised, which only unites with the primary and secondary base.
Dimethylaniline is a weak base, which, like aniline, is neutral
aSo

PRACTICAL ORGANIC CHEMISTRY

to litmus, but gives no stable salts. It is used in the prepara-
tion of malachite green (benzaldehyde green) by heating-
together dimethylaniline, benzaldehyde, and solid zinc chloride.
The product (leuco-malachite green) is then oxidised with lead
peroxide and hydrochloric acid (see p. 216),

/QHfl

HC/..................;                                          /QH5

1^0       II JC6H4N(CH8)2        ->      HO~CrJI4N(CH,),

H JC8II4N(CH3)2                            CflII4N(CH3)2

Leuco-malachite green,

/C6H8

.  ->   HOC£-C6H4N(CHS)2
\C6H4N(CH,)2
Base of malachite green.

The latter, in presence of the hydrochloric acid, is converted
into the hydrochloride,

/C6H5.
HOCe-CeH4N{CH3)2 -f

HC1 = C^QH4N(CH,).2

^CGH4:N(CH3)2C1

+

Hydrochloride of
malachite green.

Dimethylaniline is also used for the preparation of tetra-
methyldiaminobenzophenone(Michler's compound), which forms
the basis of many colouring matters, and is obtained by acting
upon dimethylaniline with phosgene (see p. 314),

/
COC12 + 2C6H5N(CH,)o = OC<

+ 2HC1.

C6H4N(CH,)2
Michler's compound.
PREPARATION 60.
Nitrosodiraethylaniline. — It is a peculiarity of the
tertiary aromatic amines, which distinguish them from the
corresponding aliphatic compounds, that they are capable of
reacting with nitrous acid. Here the nitroso-group replaces
hydrogen in the para-position to the dimethylami no-group.
The substances, thus formed, are bases, and form salts with
acids, which dissolve in water with a yellow colour. The solu-
bility of the hydrochloride of the nitroso-bases in water
distinguish them from the nitrosamines of the secondary bases?
which are insoluble.               .                                            *
AITKNDIX                                       281

Nitrosodimethylaniline is readily oxidised to nitrodimethyl-
-i niline.

It is an inlcrt-stin- fact that the nilrosnmines of the
j^tM-ondary bases undergo molecular change when acted on
xvith alcoholic hydrochloric acid. The nitroso-^roup is thereby
transferred to the para-position in the nucleus (O. Fischer),

, r-: No.c(1n,.Niicn:,

The para-nitroso derivatives of both secondary and tertiary
runiines are decomposed with caustic soda into nitrosophenol
rind alkylamine.

The formation of methylene l>luc may be explained as
follows: l>y the action of ammonium sulphide on nitroso-
tlimethylaniline, the nitroso-^mup is reduced to an amino-
j^rotip. T\\o molecules of /-aminodimethylaniline then combine
svith the elimination of ammonia to form a diphenylamine
< l<Mpivaliv<\

((. '1 1,{),X( 'i;1 1 1 ; N 1 1,    1 fi 1 1 N( \,\ I.,N(CI I,,),,

= (CMIa)aNCr,H.,.NII.CJI.,N(Cir,,)a.

The sulphur of the hydrogen sulj>hi(l(; then enters the mole-
€Mile under the oxidising influence of the ferric chloride, forming
;i thiodiphenylaiuine derivative,

II          ()            H

<('H.,).,N<;;n.,  N  <yi,,.N((:iL),,a
ii        H

II"    S    II

< >        ( >

- (Cn,,),,NCrn.,.N:CrII.,:N((''H.,),,('l.
\s/

IM^KI'ARATION  ol.
Thiocarbanilide, Thiocarbimide, Triphenylguan-
idillO.- Whereas carbon bisulphide reacts with aromatic ami no-
compounds yi<'hlin;4 a thiocarba,nilide, with primary aliphatic
amines the reaction takes a different course and thiocarbamatcs
are produced,
SILNIL.IUI
cs,, i IH\,IL;NH,,^ sc,7
•                    ....       .            X-NII.G,LIB
*""                    -282               PRACTICAL ORGANIC CHEMISTRY

The product can, however, be converted into the mustard, oil
by treatment with a metallic salt which removes hydrogen
sulphide,

/SII.NHo.C,II5
SC<              "   "     - HoS + NIIo.CoII, + SC:NC,HB.



Among the reactions appended to this preparation, the for-
mation of phenylcarbimide from phenyl mustard oil is described.
It should be noted that phenyl carbimide, like the thiocarbimicle,
unites with ammonia, amines, and more especially with alcohols
and phenols. The bases yield urea derivatives ; the alcohols
and phenols form urethanes.
C«H5N:CO + NH;) = CBHSNII.CO.NH3 Phenyl urea.
CflHfiN:CO + NH3CHS = C6HBNH.CO.NHCH3 Methyl phenyl urea.
Ct;H5N:CO + CJI5OH = C(iH5NlI.CO.OC2H5 Phenyl urethanc
Q;II5N:CO + CGH5OH = C0IIBNH.CO.OC6H0 Phenyl carbamic
phenyl ester.
The latter two reactions are frequently used for detecting
the presence of a hydroxyl group (Goldschmidt).
PREPARATION 62.
Diazobenzene Sulphate. — Whereas nitrous acid imme-
diately decomposes the primary aliphatic amines with evolution
of nitrogen,
CH3NH2 + HN0.2 = CII.OH + N2 + H2O,
no nitrogen is evolved if nitrous acid is allowed to act upon a
salt of a primary aromatic amine in the cold. The solution then
contains a diazo-salt, which is readily soluble in water. It may
already have been observed that in the salts of diazobem-
ene, the radical, diazobenzene, Cf>Hf,N2, plays the part of am-
monium, NH4, in the ammonium salts. Diazobenzene chloride,
nitrate, sulphate, &c., correspond to ammonium chloride, nitrate,
and sulphate.
CGH5N2.C1                     NH4.C1.
C8II5No.NO8                  NH4.NO8.
C6H,N2. SOJi                NH4. S04H.
The hydrate of diazobenzene, C6H5N2.OH, which would be
analogous to NH4OH, is also known as an unstable oil. Con-
AITKNDIX                                     283

siderations    of   this    kind    have    surest ed    the   alternative
formula,

e,nr,N   N

in which X stands for the acid radical (Blomstrand). The
nitrogen which combines with the acid radical is thereby quin-
quivalent, as m the ammonium salts. On the other hand, cli-
a/.obcn/,ene hydrate forms two isomeric potassium salts, one of
which is obtained by adding caustic potash to diazobenxcnc
chloride. This compound is unstable, and unites in the ordi-
nary way with phenols to form hydroxya/obciv/cne derivatives
(see Reaction 6, p. 103.1. The second one, which is obtained by
heatinj;1 the first to 130" with caustic potash, is very stable, and
does not combine directly with phenols (Sebraubcand Schmidt).
Other derivatives of dia/oben/ene exist in two forms, such as
the cyanide and sulphite. The difference has been explained
in two ways. According to one theory, the two potassium com-
pounds represent two different space configurations similar to
that of citraconic and mcsaconic acid (see p. 266) and the
oximes fsee p. 301), and are distinguished by the terms 'syn'
and l anti ' (1 lant/seh).
ruii;                                   c(.n,N
'I!                                          'II
KO.N                                     N.OK
Syii-lt'Mi.'i-M'- • li.i/MtaU' nf p.itnv,ium.        Anti-lx'iwnt' ilia/mate of potassium,
The  second   theory   ascribes   the   difference   to   structural
arrangement, and the compounds are termed dia/o- and   iso-
$  dia/.o compounds >' flamber^er).
(',;I1.,N:\()K.                            (:,,nBNK.NO.
r.i'ii.Titc tH.t/t.fatc ut" puias .iuin.              lii'ii/i-m- isodiaxotatc nf potassium.
li i-. now generally admitted that the dia/.o-salts of the
:.t mn;;cr acids, \vhi< h ha\'(» only om^ representative, are most
'.atisfactorily represented by the u diaxonium," or Blomstrand
formula, and the salts are known as diazoniuni salts.
A few of the numerous changes which the diaxonium salts
undergo are illustrated in the series of reactions which follow
the preparation, and are amonjj the most important in organic
dutinjstty. Some of these reactions are carried out on a larger
284

PRACTICAL ORGANIC CHEMISTRY

scale in Preps. 63—69. It will there be noticed that it is
unnecessary, as a rule, to isolate the diazonium salt, but that
the substance is prepared in solution, and is decomposed by
the specific reagent.
With few exceptions, all aromatic compounds which contain
a nuclear amino-group may be diazotised. At the same time
there are notable differences in the ease with which the process
is effected
PREPARATION 63.
Toluene from Toluidine.—It is often desirable to obtain
the hydrocarbon from the base. The process of diazotisation
offers the only convenient method. The diazonium salt may be
reduced by alcohol (Reaction i, p. 162) or, as in the present in-
stance, by sodium stannite. Less direct methods are the con-
version of the diazonium compound into (i) the hyclrazine (see
p. 174), (2) the acid and distillation with lime (p. 300), (3) the
halogen derivative and reduction with sodium amalgam, or,
finally (4) the phenol and distillation with zinc dust.
PREPARATION 64.
/-CresoL—This reaction resembles that of nitrous acid on
an aliphatic primary amine ; but the liquid requires to be
warmed.
PREPARATIONS 65—66.
p-Chlorotoluene, p-Bromotoluene.-—The action of cu-
prous chloride, bromide, and cyanide on diazonium chlorides was
discovered by Sandraeyer, and is known as ' Sandmeyer's re-
action.'
CBII3N.,.C1    = CJL.C1    +  No.
C0II5NfrBr    =  CGII5Br    +   N0~
C0HaN2.CN  = Q.IInCN +  No.
Some of the cuprous chloride compounds of the diazonium
salts have been isolated and analysed, and correspond to the
formula CGHr,N2CLCu.>Cl2 (Hantzsch). The formation of a
crystalline copper compound is rendered very evident in the
present preparation. A modification of Sandmeyer's reaction
is the introduction of precipitated metallic copper in place of
the cuprous salt (Gattermann).                                       *•
AN'KNDIX

285

The preparation of potassium iodide-starch paper is made
by clipping strips of filter paper into a thin solution of starch
paste to which a little potassium iodide has been added, and
drying the paper.
The oxidation of a side-chain by means of permanganate
solution is one which is commonly employed where the acid is
required. The monohalogen derivatives are readily oxidised in
this way, but greater difficulty is experienced if two halogen
atoms or other acid groups are present. The dichlorotoluenes,
for example, are only slowly attacked.
I'RKI'ARATION   67.
lodOBOtoluene. The most interesting of the compounds
belonging to this group, which were carefully investigated by
V. Meyer, is the substance prepared by shaking a mixture of
iodosoben/ene and iodoxyben/.ene (obtained by the oxidation of
the iodoso-compound) with moist silver oxide. Diphcnyl-
iodonium oxide is thus produced, which in basic properties
resembles ammonium hydrate,
c,;ii:,in j <Y,n,,i<>:. i Agon    (r(;ii;,u.oii i- Agio.,.
With hydriodic acid it forms the iodide, (C(iII,-).J.I.
I'UK PA RATION  6<>
Diazoaminobonzeiie. Dia/oamino-compounds are also
formed by the action of dia/.onium salts on primary and
secondary amines of both the aliphatic and aromatic series.
The method given in the preparation must then be modified.
The dia/.onium salt is first prepared, and the amine stirred in
with the addition of sodium acetate. The sodium combines
with the mineral acid, liberating the weaker acetic acid, which
thereby assists the separation of the tlia/.oainino-compound.
Compounds of the following formula; have been prepared in
this way.
(',;II ,N:N.C,}n I.CH..    I)iuy.c>l>Lmeno-:imiiioloUtenc
< %t;l I;,N:N. NHC.,1 I;,      I)i:t/,obcn/.c»c-cthyl:iminc.
< Y,I I;,N:N.N(C! i:,)o       Diaxoben/cne-dimethyUimme,
I )ia/.obenzene-pipcridine.
286

PRACTICAL ORGANIC CHEMISTRY

The last compound has been utilised for the preparation of
fluorobenzene, and its congeners by the action of cone, hydro-
fluoric acid,

Ct;II5N:N.C5H10 + 2HF = C6H3F + No + C5H10NH.HF.

Diazoaminobenzene undergoes the following reactions : —

r. The hydrogen of the immo-group may be replaced by acid

and alkyl radicals.    In the latter case the sodium compound is

treated with an alkyl iodide.

2. Phenyl carbimide forms a urea derivative,

C0ri5N:N.NHC8H5

CGII5N.CO = CflHBN:N.NC0I-Ic

Nco.

C6H5NI-K

3.    With strong hydrochloric acid, decomposition into cliazo-
niun^salt and amine takes place,

C6H5N:N.NHC6Ha

= C6H5N3.C1 + CBIIBNHa.

If nitrous acid is added, the second molecule of base is also
converted into diazobenzene chloride. In presence of cuprous
chloride, chlorobenzene is formed.

4.  On  boiling with  water,   diazoaminobenzene  decomposes
into phenol and base,

QHDN:N.NH.CGH5 + H,O •= CCH5OH + C6riaNH3 + N2.

5.  On reduction, it splits up into phenylhydrazine and aniline,

C8H5N:N.NHCeH8 + 2H2 = C6HBNH.NH3 + C6H5NHo.

PREPARATION 70.

Amiiioazobenzene.—The conversion of diazoaminobenz-
ene into aminoazobenzene resembles the formation of benzidine
from hydrazobenzene (see p. 148). The diazo-nitrogen seizes
on the carbon of the nucleus in the para-position to the amino-
group,

>NHo,
AI'l'KNDIX                                     287

If the para-position is already occupied, the nitrogen  takes
the ortho-position to the amino-group,

but the reaction only takes place readily where the para-position is
free. The manner in which the change is brought about has not
been satisfactorily explained, although from the fact that/-cliazo-
aminotoluene yields, on warming with aniline hydrochloride,
^-toluene a/.oaminoben/ene and /Moluidine,

CII;,.(        ' N: N. N11/        \C 113 + '('        )N IL,

:      HI.,-          ,N:N/        X;Nil,, -I CII,/        "/Nil,,,

\ ....._/         \__/        ~         \__/

it would appear as if the hydrochloride of the base were the
chief factor in the decomposition, and that the change was
rather inter- than ////nr-molecular. Aminoaxoben/ene, under
the name ol' tiirilincyclloiv, has been used as a colouring matter.
Its chief technical application at present is in the manufacture
of a class of dark blue colours, known as hitfttlhies. On reduc-
tion with tin and hydrochloric acid, it decomposes into two
moltM ules of base, aniline and />-phenylenediamine, a reaction
which is shared by most of the a/.o-compounds (see p. 176),

PRKPAKATION  71.
Phenylhydrassine, Phenylmethylpyrazolone. — The
use of phcnylhydra/,UK* or, in some cases /;~bromo~ or /-nitro-
plurnylhydra/.inc, as a reagent for the detection of aldehydes and
ketones, has been illustrated in the reactions on p. 70.
One of its most important technical uses is in the prepara-
tion of antipyriw, in which the product, obtained by the action
I V",

288

PRACTICAL ORGANIC CHEMISTRY

i.

of phenylhydrazine on ethyl acetoacetate, is acted upon with
methyl iodide.   The two reactions are represented as follows :—

CH.,.CO.CH«.COOCoHB   CIL.C~-CHo.CO

"I           + HoO +

N

N.CGH5

-- N.C6H5

Phenylmethylpyrazolone.

CH8.G=CH.CO
+CH3I=         |           |

CII3.N -- N.C6H5

Phenyldimethylpyrazolone
' (antipyrine).

The variety of syntheses into which phenylhydrazine enters
cannot be described here ; but reference must be made to the
text-book.

It should be noted that the action of phenylhydrazine on
the ketone group, and of diazobenzene salts on the methylene
group situated between two CO groups, are analogous to that
'of hydroxylamine and nitrous acid upon these two groups, of
which the following are examples : —

CO.OCoH5

I
CO

I

Mesoxalic
ester.

COOCoIi,

CI-lo

!

COOCoH5 xv

Succinic            + 0:NOH

ester.

COOC.HB

I

-f NH.,NHCGH5 = C:N.NH.QHfi + H2O

COOG,HB

NHoOH

C1N:N.C6H4 =  C:N.NII.C6H5 + HCL
COOC2H5

= CtNOII + HoO
COOCoIi,

COOC,H5
C:NOH

HoO

COOC3H5
Phenylhydrazine has been used in the synthesis of indole
derivatives.    The hydrazones of aldehydes and ketones contain-
APPENDIX

ing a methyl group are decomposed on heating with zinc chloride,
indoles being formed with elimination of ammonia. (E. Fischer.)
CII,
GIL                          |    '
I                    ,NII — C
C,,H5Nir.N:C       = O'll/           !| + NIL
I                  X -- CII
cir,
Acetone-phenylhydra/.onc.             Methyl iudole.
PREPARATION 72.
Sulphanilic Acid.— The acid characters of this substance,
which is both base and acid, are more prominently developed
than the basic character. Nevertheless it reacts with nitrous
acid like a primary amine, and forms a diazonium salt, which
has the following constitution (see Prep. 62, p. 161) : —
/N : N
QH/         I
\30.,0
Dia/obenzene sulphonic acid.
The formation of suphanilic acid is probably preceded by the
sulphonation of the amino-group,
CQH3NI-I.SO3H.
A compound of this character has been obtained which
decomposes with acids into o- and ^-aminosulphonic acid by
a process of intramolecular change (Bamberger). The fact of
the para-compound being exclusively formed at the higher
temperature may account for the production of this substance
in the present preparation.
PREPARATION 66.
Methyl Orange .--The first point to notice in this reaction
is that the diazonium salt forms no diazoamino-compound with
the dimethylanilme, but at once produces an azo-compound.
This is always the case with tertiary amines, some secondary
amines like diphenylamine and the phenols. The reaction may
be regarded as typical of the formation of all azo-colouring
matters. At least two substances are requisite in this process ;
on the one hand an aromatic compound containing an amino-
group in the nucleus, and, on the other, a base or phenol
COT EN'S ADV. P. O. C                                                          U
PRACTICAL ORGANIC CHEMISTRY

'"i1
fJ*

The first is diazotised and combined or coupled with the second.
The coupling takes place, in the case of amines, in a faintly
acid or neutral solution, in the case of phenols, in an alkaline
solution (see Reaction 6, p. 163). In all cases the diazo-group
seizes upon the carbon in the para-position to the ammo- or
hydroxyl group of the coupled nucleus. When the para-position
is already appropriated, the ortho-position serves as a link, but
no coupling ever occurs in the meta-position. The sulphonic
acid derivatives of the base or phenol are frequently preferable
to the unsubstituted compound. The dyes formed have in
consequence of the presence of the SO3H group an acid character,
which renders them capable of forming soluble sodium salts,
and adapts them better for dyeing purposes. When an azo-com-
pound is formed by coupling the diazo-compouncl with a primary
amine, the new product is capable of being diazotised and
coupled a second time. Thus a tetrazo-compound is formed
containing a double diazo-group ~N:N~. Aminoazobenzene,
when diazotised, forms diazo-azobenzene with nitrous acid, which,
like a simple diazo-compound, reacts with the phenols,
C6H5N:N.CHH4NILHC1 + UNO, = C0I-I5N:N.CuH4N.j.Cl -I- 2lIaO.
CttH5N:N.C6H4No.Cl + C0II5ONa
= CBHBN:N.C6IT4N:N.C6H4OII + NaCl.
If aminoazobenzene is sulphonated with fuming sulphuric acid,
and the product again diazotised and coupled with /3-naphthol,
Biebrich scarlet is formed,
/SOj,H
C6H4<                 /SO,II
\N:N.C6H/
\N:N.C10HflOI-I.
Biebrich scarlet.
If in the last phase the different sulphonic acids of /3-naphthol
are employed, various shades of red, known as Crocciiis^ are pro-
duced. Thus it appears that the colour deepens from orange to
red with the introduction of a second azo-group.
This is not the only method of forming tetrazo-compounds.
Each ammo-group of a diamine may be diazotised and coupled.
Benzidine and its homologues, which have been utilised in this
way, have a special value for the cotton dyer, as the shades pro-
duced are not only very brilliant, but, unlike the majority of
29I

colouring matters, arc xubstanth'e. colours, i.e., possess the pro-
perty of attaching themselves to the cotton fibre without the aid
of a mordant. Cf/wt m/.s- and hetizoflitrfiuruis are combina-
tions of bcn/idinc and its homologues with the sulphonic acids
of naphthol and naphthylamine. The following- js the constitu-
tion of Congo red, the simplest of these compounds, which is
used in the form of its sodium salt : —

Ml.,
N:N. (',„!!,

\SO.,,\ii

.Nil,

Attention should be drawn to the fact that azobenzenc,
although a, brightly coloured substance, is without dyeing' pro-
perties, />., it is not a colouring matter, whereas aminoazobenz-
ene and methyl onmgc are true dyes. They all three contain
the a/o-group ( N:N \ called by Witt a chroniophore, united
to two aromatic nuclei ; but in the case of aminoaxobenzene
and metli\'l oi'an^e, (Hie of these nuclei contains a basic group,
NIL, or N(('II:,),,. Ii will also have been observed that the
combinations with phenols likewise result in the production of
colouring matters. It. would appear, therefore, as if there were
at least two essentials to a dye, a fundamental or mother sub-
stance like axobenxene, termed a chroniogenic compound, and
an ammo- or hydroxyl group, called an aitxochromc. The same
thing has been observed in the case of other colouring matters
(see Note on I 'rep. 103, p. 313).
Most of the a/.o-colours split at the double link, on reduction
with stannous chloride and hydrochloric acid, forming two
molecules of base. Methyl orange yields sulphanilic acid and
dimethyl /-phcnylenediamine,
S(;.,li.CViriN:NA%,;lI4N(CU.i).. I all.,
' = SO..I I.C0U4Nlla +
292

PRACTICAL ORGANIC CHEMISTRY

PREPARATION 74.
Potassium Benzenestdphonate.—The formation of sul-
phonic acids by the action of sulphuric, acid, &c., on the aromatic
hydrocarbon is a special property of aromatic hydrocarbons,
although, in a few cases, paraffins have been found to react in a
similar manner. The process is called " sulphonation." In
place of cone, sulphuric acid, fuming sulphuric acid, i.e., an acid
containing varying proportions of sulphur trioxide (see Prep. 109,
p. 226), and, occasionally, chlorosulphonic acid, C1SO2OH, are
used. In the two latter cases sulphones are sometimes formed
as a by-product,
2C6H6 + SO, = (C(;H5),SO., + H,0.
2QH« + C1S03OH = (C(jlIB)2SOa + HC1 4- H..O.
The sulphonic acids are also obtained by the oxidation of
thiophenols, a reaction which, at the same time, indicates their
constitution,
QH8SH + O., = C6H5SO,II.
TTie majority of aromatic sulphonic acids are very soluble in
water, and are difficult to obtain in the crystalline form. On
the other hand, the sodium or potassium salts generally crystal-
lise well, and it is customary to prepare them by pouring the
sulphonic acid directly after sulphonation into a strong solution
of sodium or potassium chloride (Gattermann).
The sulphonic acids decompose on heating into the hydro-
carbon and SO3. This reaction is greatly facilitated by heating
with cone, hydrochloric acid to 150—180° (Jacobsen), or by
passing superheated steam into the sulphonic acid mixed
with moderately strong sulphuric acid (Armstrong).
This method is sometimes used for separating hydrocarbons,
one of which is more easily sulphonated than another. The
sulphonic acid is separated from the unchanged hydrocarbon,
and the hydrocarbon is then regenerated from the sulphonic
acid.
The salts of the sulphonic acids undergo the following re-
actions :—
T. By fusion with caustic alkalis, phenols are prepared (see
Preps. 106 and 219),
C6H,SO,Na + NaOH = C«HaOH + Na2SO3.
APPENDIX                                     293

2.     i>y  distillation with  potassium cyanide, the nitriles are
obtained,

(V.N-.SO.jK  |   KCN = (yir.CN -I- K,,SOa.
ii   •>     <»                         i)   i)               j     «j§

3.   11 y   fusion with sodium   formate, the   sulphonic  group is
replaced by carboxyl,

r,;Il:iS():,Na   !   IICOONa ---C,lI5COONaH- NallSOg.

4   l>y the action of phosphorus pentachloride the sulphonic
chloride is obtained,

rt;U,S()3K -I   VL\ = (yiflSOXl + POC13 + KC1.

PRKI'ARATION 75.

Benzenesnlphonic Chloride.— The sulphonic chlorides
differ from the carboxylic chlorides in being" very slowly decom-
posed by water. They read, however, in an analogous fashion
with alcohols, phenols, and amines in presence of caustic soda.

The behaviour of primary, secondary, and tertiary amines
has been sut^ested as a basis of separation of these three classes
of compounds. The primary amines usually form compounds
with tin1 sulphonic chloride, which dissolve in caustic soda ; the
derivatives of the secondary amine are insoluble, whereas the
tertiary amines do not re;ict with the sulphonic chloride (Hins-
bcr^). The* method cannot always be employed.

On reduction of the sulphonic chloride with zinc dust and
water, the xinc salt of the sulphinic acid is formed,

2('(jIIfiS(),,ri -I- 2/n •= (Q.II-iSO.J.jXn + XnCl2.

The arid is separatee! from the xinc salt by boiling with
sodium carbonate, filtering from xinc carbonate, and decom-
posing the soluble sodium salt with sulphuric acid, which pre-
cipitates the sulphinic acid.

The sulphinic acids are unstable compounds. They are readily
oxidised to sulphonic acids ; on fusion with alkalis they are con-
verted into the hydrocarbon and alkaline sulphite,

CI!.S().N:i + NaOII =

on reduction they form thiophenols,
*             Ct;ll,rS(UI -i  2llo -- QIUSIl -I   2lloO.
tf     T                  294               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 76.                                               ]
Phenol—Fusion of the alkali  salt  of the  sulphonic acid               i
with caustic soda or potash is a common method for preparing              j
phenols (see Prep. 106, p. 219).    Phenols correspond in consti-               '
tution to the tertiary alcohols of the aliphatic series, but differ
in  their more negative  character.    The phenols  dissolve  in              j
caustic alkalis, forming alkaline phenates, which are, however,              '
decomposed by carbon dioxide.    In this way a phenol may be             I
separated from an acid.    The solution in caustic soda  is satu-
rated with carbon dioxide,  and  the phenol is then extracted
t                          with ether or filtered  off.     The entrance of nitro-groups into
the  nucleus converts phenols into strong acids (see Preps. 79
and 80).
*/* •                          The various reactions which the phenols undergo are illus-
trated in Preps. 79—84.
The technical method for obtaining phenol is by shaking out
„    •    :,                   with caustic soda the " middle oil" of the coal-tar distillate, after
* '                         some of the naphthalene has crystallised out.    The phenol dis-
solves in the alkali, and  is then removed from insoluble oils.
§The alkaline liquid is acidified, the phenol separated, distilled,
and finally purified by freezing.
i
'. "                                                     , PREPARATION 77.
|                              Anisole.—The preparation of anisole from phenol is analo-
gous to Williamson's synthesis of the ethers (see p. 236), but the
ethers of phenol cannot be obtained by the action of the alcohol
on the phenol in presence of sulphuric acid. This reaction can,
however, be effected in the case of the naphthbls (see p. 316).
Another method of replacing hydrogen by methyl, in addition
to the use of alkyl halide and alkyl sulphate, is by the action of
diazomethane on the phenol :
N\
CflIIaOII + || ;>CHa = CflH5OCH3 + No.
N'
The methyl group in anisole can be split off, and the phenol
regenerated by heating with HC1 or HI,
CBH5OCUS + III = CIT.,I + C,,IIBOII.
The latter reaction has been made the basis of a quantitative
APPKNDIX                                   295
method for determining the number of mctlioxyl groups (OCH-.j
present in a compound iZcisel, see p. 220).
PREPARATION    78.
Hexahydrophenol—llic method of Sabatier and Sen-
derens for the reduction of organic compounds is very generally
applicable. It consists in passing the vapour of the organic
compound mixed with - hydrogen over finely divided metals,
especially nickel, as in the example given. Aldehydes and
Uotoni's arc. reduced to alcohols*, olefincs to paraffins, and, in
the aromatic series, hydrogen is taken up in the nucleus and
hydrocyclic compounds result. The hydrocarbons form cyclo-
paraflms ; the phenols, cyclic alcohols ; the bases, cyclic
amines, &c.
PREPARATION  79.
o- and p-Nitrophenol. The action of nitric acid on
phenol is much more energetic than it is in the case of
hen/em.'. To obtain the. mono-derivatives, the acid has, in
consequence, to be diluted.
The entrance of the nilro-group renders the phenol more
strongly acid, so that the nitrophenols, unlike the phenols, form
stable salts with alkaline; carbonates. It should be noted that
the nitro-groiip enters the ortho- and para-position, but not the
meta-position to the Oil group, according to the general rule
explained on p. 274. Moreover, the ortho-compound is more
volatile than the para-compound. Compare o- and />-hydr-
oxybcn/.aldehyde (Prep. Sj, p. i 88).
PREPARATION   80.
Picric Acid.......The presence of three nilro-groiips converts
the phenol into a strong acid. Picryl chloride, which is formed
by the action of PC1-, on the acid, behaves like an acid chloride,
is decomposed by water and alkalis and forms picramide or
trinilraniline with ammonia,
<',jll.,(N0,);!n  I  N1IS r- c:(i!I,(NO,):,Nn,, -1- IIC1.
Note that the throe nitro-groups occupy meta-positions in
regard to one another ; ortho- or para-positions in reference
to t4ic hvdroxvl group.
296

PRACTICAL ORGANIC CHEMISTRY

PREPARATIONS Si — 82.

Phenolphthaleiii. — The action of phthalic anhydride on
phenol takes place in two ways. When equal molecules of the
substance react in presence of cone, sulphuric acid, hydroxyan-
thraquinone is formed (Baeyer),

CJI

/co\

0

C0

/\
= C(1H4<       >C0IT.,OH + 11,0.

X-X       '

It is by a similar process that alizarin has been synthesised
with the object of ascertaining its constitution (see Notes on
Prep. 1 10, p. 316), When two molecules of phenol and one mole-
cule of phthalic anhydride are heated together with cone, sul-
phuric acid, then phenolphfhalein is formed (Baeyer). Its
constitution has been determined by its synthesis from phthalyl
chloride and benzene by means of the " Friedel-Crafts3 reaction"
(see Notes on Prep. 100, p. 309), Phthalyl chloride and benzene
yield in presence of A1C13 phthalophenone,

C jClo

U;C«II5

=    QH.

CO

CO

Phthalophenone.

Phthalophenone is then converted successively into dinitro-,
diamino-, and, finally, by the action of nitrous acid, into clihydr-
oxyphthalophenone or phenolphthalein,
r^C(;U,                   r   C6H4N0.2

QH4-

/

0

CO

Phthalophenone.

CGTI4\/W
CO

Dinitrophthalophenone.

C6H4

r    C(iH4NIlo

^QII.NH;

cu' /°

Mi1 M   \/

CO

Diuminophthalophenone.

4\/"
CO
Phenolphthalein.
An important group of colouring matters, known as the
" rhodamines," is obtained from phthalic anhydride and m-
aminophenol and its derivatives. They have a constitution similar
Ai'PKNDIX

to that, of iluoresccin.    The  simplest of these 'compounds  is
represented by the following formula :—

etiH,NIL
C)

1}R Kl'A RATION   83.

Salicylaldehyde, p-Hydroxybenzaldehyde.—"Reimer's

reaction" for the preparation of hydroxyaldehydes from phenols
is applicable to a very lar^'e number of monohydric and-poly-
hydric phenols. The substitution of two II atoms by two alde-
hyde groups sometimes occurs, as in the case of resorcinol. An
analogous reaction is that of caustic potash and carbon tetra*
chloride on phenol, which yields chiefly /»-hydroxybenxoic acid,

.,OII

(',11,011   !  CCI.,  I  SKOII ~ (.Y.HI-''             -I- 4KC1 -!• 3ILO.

NCOOIv

PREPARATION    $4.
Salicylic Acid. —The reaction was discovered by Kolbe,
and is known as tl Kolbc's synthesis." It will have been ob-
served that it takes place in t\vo steps. Sodium phenylcarbdnate
is iirst formed, which then undergoes intramolecular change
•with the production of sodium salicylate (Schmidt). The tech-
nical process is carried out in autoclaves, in which carbon
dioxide is passed into the sodium phenate under pressure at
1 20 130'. It is a curious fact that the use of potassium phenate
yields, especially at a hiyh temperature (220' ), almost exclusively
the /<>»hydroxybeim>ate of potassium.
The above reaction may be applied in the case of other
phenols.
I'RKPA RATION    85.
Quinone and Quinol. Ouinone, which was originally
obtained by the oxidation of quinic acid (the acid associated
298

PRACTICAL ORGANIC

with quinine in cinchona bark), is now prepared from aniline.
The aniline, in process of oxidation to quinone, appears to pass
through the following intermediate stages,

xNHo

/         —

^Oll

The aniline is first oxidised to phenylammonium oxide, which
changes into phenylhydroxylamine. The latter also under-
goes intramolecular change, being converted into /-amino-
phenol, which is finally oxidised to quinone (Bambcrger).
It may also be obtained "by the,oxidation of para-derivatives of
aniline, such as /-phenylenediamine, sulphariilic acid, p.
aminophenol, &c. Other amino-compounds and phenols yield
corresponding quinones, and it can even be prepared from an
amino-compound or phenol, if an alkyl group occupies the para-
position, as in the case of mesidine, which loses a methyl group
and yields jw-xyloquinone. Quinone is sometimes regarded as a
superoxide (Graebe), sometimes as a para-diketonc (Kittig).

HC<

O
O

,CH

HC/
II cJ

c

Superoxide formula.

cn

r formula.

The facts in favour of the first are that quinone, like a peroxide,
has a strong oxidising action, that on reduction it yields, not a
glycol, but a dihydroxybenzene ; moreover, with PCI.-, instead
of a tetra-chloro-derivative, a dichloroben/.cnc is formed. In
favour of the ketone structure is the formation of a mono- and
di-oxime (Golclschmidt),

CO

C:N()IT

IIC

Hc.;   ';cn

CrNOH

JIC

iid

(MI
C:NOir.
APPENDIX

I'henylhydra/ones <".re not formed, .as phcnylfiydrazine acts as a
reducing ;igent and produces quinol.^

The constitution of quinhydrohe. tfep intermediate
formed by the reduction of quinoneS,^ <&\da&jq<ft», oT""
represented by the formula,                     ^^^^IJ. ~ ^.«*•-••••

/)----C(OII)

" 4\ nc\Jui

For the formation of dimcthylquinone, sec p. 251.

Pkl<: PA RATION    86.

Benzyl Chloride.--The action of chlorine on boiling
toluene is quite distinct from the action which occurs in the
rold or in presence of a u halogen carrier " (see pp. 252, 271).
In the present instance substitution takes place in the side-
chaiu. It is a curious fact, however, that: clllorinc produced by
elect rolysis \\\ presence of boiling toluene mainly enters the
nucleus.

P.y prolonged action all three hydrogen atoms of the side-chain
may be replaced, and the following compounds obtained: —
Ct.lI,(ClU;i     Ben/yl Chloride.
(',';! r,CI ICK,    iJciixal Chloride.
C,jII..(CCl.,       ncny.otridiloride.

Hydrocarbons containing the halogen in the side-chain may
be L'.cncrany, though not. invariably distinguished, by their
irritating action on the eyes and mucous membrane of the nose,
from those in which the halogen is present in the nucleus.
Moreover, the halogen in the side-chain is much more readily
substituted or removed than when it occurs in the nucleus. In
this respect the above compounds resemble the members of the
aliphatic series (alkyl and alkylene halides). Benzyl chloride is
decomposed by water, ammonia, and potassium cyanide, forming
ben/yl alcohol, ben/yl cyanide, and benzylamine.

c,;ii,ciu:i ! ju) - (Viir,cii,OTi -i- nci
c(iH,cn,ci i KCN .- (;,,nBciiaCN + KCL

Jlcn/yl cyatiidf,

(VJI^'H-/1!  I  2NII:,.....C.-HnCH.jN'IIo •)  NH4C1.

300               PRACTICAL ORGANIC CHEMISTRY

'                            It is also much more easily oxidised than toluene to benzole
acid,
< i                                                              Q5IIr,CILCl -i- Oo = CaIInCOOII + HC1.
Benzal chloride and -benzotrichloride are also decomposed by
i       •                  water, the former in  presence of calcium carbonate, and the
i                       latter at a high temperature^ yielding, in the one case, benxalde-
"                       hyde, and in the other, benzoic acid,
CJIflCHCla + II.20 = C,jIIsCOII + 2IIC1.
Benzaldrbyile.
C(JU5CC1, + 2lI2O = C,5HaCO.OII + 3IIC1.
J                                                                                                Benzoic acid.
^                                                    PREPARATION 87.
Benzyl alcohol may be also obtained by the action of caustic
potash on benzaldehyde (see Reaction 4, p. 197).    This reaction
JH'*j}                     is  specially characteristic of cyclic-compounds containing  an
!   11                      aldehyde-group in the nucleus, although  some of the  higher
aliphatic aldehydes behave in a similar fashion (Cannizzaro),
2CCH5COH -I- KOH = C0H5CH,Oir + QIIsCOOK.
Benzyl alcohol.    Potassium benzoate.
Benzyl alcohol has the properties of an aliphatic alcohol, and
not those of a phenol. On oxidation, it gives benzaldehycle
and benzoic acid, and it forms benzyl esters with acids or acid
chlorides,
CflI!riCO.OCHa.C0Hfl.
Ben/yl ben/oate.
PREPARATION 88.
Benzaldehyde.—The aldehydes of the aromatic series
may also be obtained by the oxidation of a methyl side-chain
with chromium oxychloride. The solid brown product,
C(.H5CH3(CrO2Cl2)2, formed by adding CrO2Cl2 to toluene,
dissolved in carbon bisulphide, is decomposed with water, and
benzaldehyde separates' out (Etard). Other methods for pre-
paring aromatic aldehydes are (i) the Friedel-Crafts reaction, in
which a mixture of carbon monoxide and hydrogen chloride are
passed into the hydrocarbon in presence of aluminium chloride
and a little cuprous chloride,
/CH.,
C6H,.CH8 + HC1.CO = Ct!M/       '    + HC1 ;
APPENDIX                                   30I

(2) also by passing a mixture of hydrogen cyanide and hydrogen
chloride into a phenol ether in presence of A1C13,
/OCIL,
C6IIBOCII3 + HCN.IIC1 - Q-M4<         "     + IIC1.
XCII:NH
The product is then hydrolysed with hydrochloric acid
(Gattermann),
/OCII3                          /OCII,
Q>n4<               +ii«o = c;Hii4<:
XCII:NII       "                -CllO
(3) Grignard's reaction can also be used for preparing aromatic
aldehydes (p. 308).
The numerous reactions which benzaldehyde undergoes are
described in this preparation, and in some of the subsequent
ones (see Preps. 93-97).
On reduction, benzaldehyde yields, in addition to benzyl
alcohol, a pinacone known as liydrobenzoin,
c,,iiacoii                  cyr5cnoH
+ H3      -               I
QjIIgCOH                         CBII5CIIOII
Hydrobenzoin.
PREPARATION 89.
a- and /3-Benzaldoximes.—The existence of two isomeric
benzaldoximes was first observed by Beckmann in 1889, vyho
explained their relation by a difference 'in structure.
C6H5CH:NOH              C6H5CH.NH
\/
O
a-Benzaldoxime.                    jS-Benzaldoxime.
In the following year Hantzsch and Werner published their
theory, by which the greater number of isomeric oximes both of
aldehydes and ketones have found a satisfactory explanation.
These compounds were not structurally but stereo-isomeric, the
relation being similar to that which exists between fumaric, maleic
or mesaconic and citraconic acids (p. 265), or again between the
two diazotates of potassium (p. 283), and which may be
represented as follows :
C6H5.C.H                      C8H8.C.H
HO.N                                 N.OH
a-Benzaldoxime.                                  jS-Benzaldoxime.
PRACTICAL ORGANIC CHEMISTRY

It will be easily understood from these formula why the /3-com-
pound should yield benzonitrile with acetic anhydride whilst the a-
compound does not. The proximity of hydrogen and hyclroxyl in
the former case facilitates the formation and elimination of water.
In this way the configuration of most of the aldoximes may be
ascertained.

PREPARATION 90.

Benzoic Acid.—The oxidation of the side-chains in aromatic
hydrocarbons is a matter of considerable interest, as illustrating
the difference of stability of the side-chain and nucleus, and also
the influence which the relative positions of the side-chains,
where more than one is present, exert in presence of oxidising
agents.

The oxidation of the side-chain of an aromatic hydrocarbon,
when more than one is present, takes place in successive steps.
Thus, mesitylene is converted into the following compounds on
oxidation ;

. C0H3(CH3)3CO.OII    Mesitylenic acid.

Mesitylene, C6H3(CU3)3 —> CGH3CH3(CO.OJ I)a    Uvitic acid.

C«H3(CO.OH):,

Trimesic acid.

The reagents usually employed are (i) chromic acid or
potassium bichromate and sulphuric acid, (2) dilute nitric acicl
and (3) potassium permanganate in alkaline or neutral solution.
The action of these upon the side-chain, when more than one
side-chain is present, depends upon their relative position.
Thus, for example, potassium bichromate and sulphuric acicl
either does not act, or completely destroys the compound when
the side-chains occupy the ortho-position (Fittig), whereas the
para- and meta-compounds yield the corresponding carboxylic
acids. ' This is true also of substituted hydrocarbons with one
side-chain ; thus with nitric acid m- and j^-nitrotoluene give
m- and ^-nitrobenzoic acid, whilst the ortho-compound is either
unattacked or destroyed. If, however, the substituent is a
halogen and the oxidising agent nitric acid, the m eta-compound
is least, and the para-compound most acted on. Dilute nitric
acid or alkaline permanganate are most serviceable for oxidising
APPENDIX

side-chains where only one side-chain is to be converted into
carboxyl on account of their less energetic action.

The oxidation of a halogen-substituted side-chain by the usual
oxidising agents is much more readily accomplished than that
of a simple alkyl group. A similar case is that of naphthalene
telrachloride, C10HiSCl4, which, though an additive compound, is
much more readily converted into phthalic acid than naphthalene
itself.

PREPARATION 91.

m-Nitro-, m-Amino-, m-Hydroxy-beiizoic Acids.—

This series of compounds merely furnishes an exercise in the
processes previously described and illustrates the application of
the same reactions in the case of a substituted benzene derivative
containing a nitro-groiip. It also illustrates the manner in which
meta-compounds of benzoic acid may be indirectly prepared
where a direct method is inapplicable.

PREPARATION 93.
Benzoin.—As a small quantity of potassium cyanide is
capable of converting a large quantity of benzaldehydeTinto
benzoin, the action of the cyanide has been explained as follows :
The potassium cyanide first reacts with the aldehyde and
forms a cyanhydrin, which then condenses with another molecule
of aldehyde, hydrogen cyanide being finally eliminated
(Lap worth),
/OH                                         /OH
CUIISCH<        + QH8CHO == QH5.Cf------CH(OH)C6Ha.
\CN                           XCN
= QH5.CO.CH(OH).QH5 + HCN.
The same reaction occurs with other aromatic aldehydes
(anisaldehyde, cuminol, furfurol, &c.)«
Benzoin yields hydrobelizbin on reduction with sodium
amalgam, and desoxybenzoin, C(!Hr>CO.CH.,.C(iH5, when reduced
with zinc and hydrochloric acid.
The latter, which contains the group CO.CH.,.C(iH-, behaves
like malonic ester, the hydrogen of the methylene group being-
replaceable by sodium, and hence by alkyl groups.
304               PRACTICAL ORGANIC CHEMISTRY

I

PREPARATION 94.
Cinnamic Acid.—The reaction, which takes place when an
aldehyde (aliphatic or aromatic) acts on the sodium salt of an
aliphatic acid in presence of the anhydride, is known as
" Perkin's reaction," and has a very wide application. Accord-
ing to the result of Fittig's researches on the properties of the
unsaturated acids described below, the reaction occurs in two
steps, The aldehyde forms first an additive compound with
the acid, the aldehyde carbon attaching itself to the a-carbon
(/.£., next the carboxyl) of the acid. A. saturated hyclroxy-acid is
formed, which is stable, if the a-carbon is attached to only one
atom of hydrogen, as in the case of isobutyric acid,
CII3
CH3X                                              I
Ct;H5CHO +         >CH.COOH = CJI5CH(O1I),CCOO1I.
CII/                                         |
C1I,
If, as in acetic and propionic acids, the group CH2 is present
in the n-position, water is simultaneously split off, and an
unsaturated acid results,
CH3
CuIi3CHO + CHj.CH2.COOH = C6H5CH:C.COOH + H2O.
a-Methylcinnamic acid.
That a-methylcinnamic acid is formed and not phenyliso-
crotonic acid according to the equation,
CGH5CHO + CHo.CHo.COOH = C6Hr,CH:CH.CHo.COOH + IL/J,
Phenylisocrotonic acid.
follows from Fittig's researches, and depends upon the marked
difference exhibited by the two principal groups of unsaturated
acids, viz., the a/3 acids, which have the double link between
the first and second carbon from the carboxyl, and /3y acids, in
which the double link lies between the second and third
carbons. Methylcinnamic acid belongs to the first group,
whereas phenylcrotonic acid belongs to the second group.
It may be noted in passing that this reaction bears a close
resemblance to that studied by Claisen, which occurs in
presence of caustic soda solution between -aldehydes or ketones
on the one hand, and compounds containing the
APPENDIX

CHo.CO.      Benzaldehyde  and  acetone  combine under these
conditions to form benzylidene- and dibenzylidene-acetone3
C6H5COH + CH3.CO.CH3= C6H5CH:CH.CO.CH3.
Benzylidene acetone.
2C0H5COH + CH3.CO.CH3 = C6HBCH:CH.CO.CH:CH.C6H3.
Dibenzylidene acetone.
All the unsaturated acids have the following properties in-
common. They form additive compounds with nascent
hydrogen, halogen acids, and the halogens. On oxidation with
alkaline permanganate in the cold, they take up two hydroxyl
groups to form a dihydroxy-derivative, and, on further oxidation,
ultimately divide at the double link. Cinnamic acid may be
taken by way of illustration. On reduction it forms phenyl-
propionic acid, with hydrobromic acid, /3-bromophenylpropionic
acid (the bromine attaching itself to the /3-carbon, see p. 253),
with bromine a/3-dibromophenylpropionic acid, on oxidation with
permanganate, phenylglyceric acid and then benzaldehyde and
benzoic acid,
QI15CH:CH.CO.OH + H2          = C6H5CHo.CH2.CO.OH.
Phenylpropionic acid.
CBH5CH:CH.CO.OH + HBr         = CfiH6CHBr. CHo.CO. OH.
Phenyl /3-bromopropionic acid.
C6HBCH:CH.CO.OH + Br2          = C6H5CHBr.CHBr.CO.OH.
Phenyl a/3-dibromopropionic acid.
C(iH5CH:CH.CO.OH + H2O + O = CeH5CHOH.CHOH.CO.OH.
Phenylglyceric acid.
CCHSCII:CH.CO.OH + 2O.2         = C6H5COH + 2CO2 + H2O.
Benzaldehyde.
The chief difference between the two groups of a/3 and /3y
unsaturated acids lies in the behaviour of the additive compounds
which they form with hydrobromic acid and bromine.
In the case of the a/3 acids, the hydrobromide of the acid, on
boiling with water, yields the corresponding (B hydroxy-acid,
and, on boiling with alkalis, a mixture of the original acid and
the unsaturated hydrocarbon, formed by the elimination of
carbon dioxide and hydrobromic acid,
1.    C,H,CHBr.CIL,COOH + H2O = C0HBCHOH.CH3.COOH4-HBr.
*    l                    ~                                   /3-Oxyphenyl-propionic acid.
2.    C,IIrCHBr.CH.,.COOH + NaOH = CBH8CH:CH.COOH + NaBr
0                        -                                            Cinnamic acid.          + H2O.
^    C,.II,CHBr.CII.,.COOII +NaOH = C6HaCH:CI-Ia + CO2 +KaBr
°'      ^b    °                  -                                          Styreiie.                  4-IJ,O.
COHEN'S ADV. P. O. C.                                                           x
306

PRACTICAL ORGANIC CHEMISTRY

The hydrobromides of ]8y unsaturated acids like /3-phenyl-
crotonic acid behave quite differently. On boiling with water,
lactones are formed, i.e., inner anhydrides of oxy-acids,

CdH5CHBr.CH2.CHo.COOII - C6II5CH.CH2.CII2 + HBr.

I
O-

_o

Phenylbutyrolactone.

The readiest method for distinguishing a /3y-acid, especially
of the aliphatic series, is to heat the acid with a mixture of
equal volumes of. cone, sulphuric acid and water to about 140'.
The lactone is formed if a /3y-acid is present, whereas an «#-acid
remains unchanged. By diluting, neutralising with sodium
carbonate, and extracting with ether, the lactone is separated,
the a/3-acid remaining in solution.

An interesting relation exists between the two groups of acids.
It has been found that, on heating j3y-acids with caustic soda
solution, a shifting of the double link on the apposition takes
place,

C8H8CH:CH.CHa.COOH = C8HflCH2.CH:CH.COOLL

y       ]8       a                                                         /3       a

PREPARATION 95.

Hydrocinnamic Acid.—The preparation illustrates the use
of sodium amalgam as a reducing agent. It should be noted
that hydroctnnamic acid may be also obtained from malonic
ester by acting upon the sodium compound with benzyl chloride,
then hydrolysing and removing carbon dioxide,

CGH5CHoCl + NaCH(COOC,Ha)., •> C(iHnCH.,CH(COOCoH5),
-> C6H5CH2.CH(COOH)'2 + C6H8CH2.CH2COOH.

PREPARATION 96.
Mandelic Acid.—The reaction furnishes a simple and
general method for obtaining hydroxy-acids from aldehydes or
ketones by the aid of the cyanhydrin. The formation of the
cyanhydrin may be effected in the manner described or by the
action of hydrochloric acid on a mixture of the aldehyde or
ketone with potassium cyanide, or, as in the case of the sugars,
by the use of liquid hydrocyanic acid and a little ammonia,
APPENDIX                                     307

Mandelic acicl was originally derived from bitter almonds, and
can be obtained by the action of baryta on amygclalin, the
glucoside of bitter almonds, which breaks up into glucose and
manclelic acid. Mandelic acid contains an asymmetric carbon
atom, and is capable, therefore, of being resolved into optical
enantiomorphs (p. 262). This has been effected by fractional
crystallisation of the cinchonine salt, from a solution of which
the dextro-rotatory component first separates. Another method,
known as the biochemical method, is to cultivate certain low
organisms in a solution of a salt of the acid when one of the
components is destroyed or assimilated. Thus ordinary green
mould (penirilliuiii) assimilates and removes thekevo component,
leaving a dextro-rotatory solution. These two methods, together
with the separation of the enantiomorphous crystalline forms
described on p. 123, comprise the three classical methods devised
by Pasteur for resolving inactive substances into their active
components. Mandelic acid may also be resolved by partial
hydrolysis of its esters by the ferment "lipase" (Dakin) ai.d
also by the partial esterification of the acid with an active alcohol
such as menthol (Marckwald).

PREPARATION 97.
Phenylmethylcarbinol.—The method of Grignard, of
which this preparation serves as an illustration, has received a
very wide application. The following is a brief and incomplete
list of these reactions, in which the organic radical (R) represents
within certain wide limits both an alkyl and aryl group :
Hydrocarbons. The magnesium compound is decomposed
by water,
RMgl + IIoO - R.H + Mgl(OH).
Alcohols may be obtained from aldehydes, ketones, esters,
acicl chlorides, and anhydrides,
R.                         1\      ,OMirI       Rx      ,OII
xco + RMo-i ->   xc;    " ->    >c<
R.                        fc            R      XR                 R'        R   .
^)           .                /OMgl       ^     /OMgl       ^   (    OH
v                              \R  "   J         \R                XR.
X  2
Aldehydes can be prepared from dimethylformamide
HCO.NRR -{- RMgI->HCR(OAIgI)NRR->RCHO + 3STHRR +
and from formic and orthoformic ester,

HCO.OCoHg -f RMgI->RCHO + MgI.OC2H5.
Ketoncs may be obtained from cyanogen, cyanides, or

/NMgl
RCN + RMgl -> R.C<          •> R.CO.R + NH3

Acids are produced by passing carbon dioxide into tlie ether
solution of the magnesium alkyl compound,

xOMgI            ,OH

RMgl -f- COa -> R.C/          -> R.O;        + MgI(Ol J ).





In addition to the above, Grignard's reagent has been utilised
in preparing defines, ethers, ketonic esters, hydroxy-acids,
quinols, amides, hydroxylamines, &c., for details of whlcii books
of reference must be consulted.1

PREPARATION 98.

; Benzoyl Chloride.—The formation of esters by fhe action
of benzoyl chloride or other acid chloride on an alcohol or phenol
in presence of caustic soda is known as the " Schotteii- 13aumann
reaction." The reaction may also be employed in tlie prepara-
tion of derivatives of the aromatic amines containing- £m acid
radical, like benzanilide, C0H6NH.CO.C0H5,

NH.,C6H3-fNaOH = C(IIIflCO.NHC6H6+NaCl+ IIaO.

PREPARATION 99.
Ethyl Ben25Oate.—The method of Fischer and Speier for
the preparation of esters, by boiling together the acid, with the
alcohol containing about 3 per cent, of either hydrocllloric acid
1 Schmidt, Ahrens* Vortrtigei 1905, 10, 68.                                ^
APPENDIX                                     309

or cone, sulphuric acid, can be adopted in the majority of cases
with good results, and has many advantages over the old
method of passing hydrochloric acid gas into a mixture of the
alcohol and acid until saturated. Read Notes on Prep. 15,
p. 247.

PREPARATION 100.

Acetophenone.—The " Friedel-Crafts' reaction," of which
this preparation is a type, consists in the use of anhydrous
aluminium chloride for effecting combination between an
aromatic hydrocarbon or its derivative on the one hand, and a
halogen (Cl or Br) compound on the other. The reaction is
always accompanied by the evolution of hydrochloric or hyclro-
bromic acid, and the product is a compound with A1C13, which
decomposes and yields the new substance on the addition of
water. This reaction has been utilised, as in the present case,
(r) for the preparation of ketones, in which an acid chloride
(aliphatic or aromatic) is employed,

CGTT6 -I- Cl.CO.CIL = C0H5.CO.CH3 + HCL

Acetophenone.

Cflllfl + Cl.CO.CfiTTs = CflHrt.CO.CflHe + TICK

Benzophenone.

If a substituted aromatic hydrocarbon is used, the ketone
group then enters the para-position, or, if this is occupied, the
ortho-position. Substituted aromatic acid chlorides may also
be used, and if the acid is dibasic and has two carboxyl chloride
groups, two molecules of the aromatic hydrocarbon may be
attached. If phosgene is used with two molecules of benzene,
bemophenone is obtained,

2CCHG + C12CO = C6HB.CO.C0H0 + 2HC1.

Benzophenone.

(2) This reaction may be modified by decreasing the propor-
tion of the hydrocarbon, and an acid chloride is then formed.,

:(.ntj H- cicoci = COHB.COCI + nci.
Benxoyl chloride,
3io

PRACTICAL  ORGANIC  CHEMISTRY

(3) With an aromatic hydrocarbon and a halogen derivative
of an aliphatic hydrocarbon or aromatic hydrocarbon .substi-
tuted in the side-chain, new hydrocarbons may be built up (see
Prep. 102, p. 214),

QI-I,. + CoIIr,Br = C,;Hfi.C2H, + IIBr.

Ktliylben/ene.

C8H6 + ClCHo.CV.IIn ~ C,iII5.CII2.C,sHB + MCI,

Diphenylmethane.

3CfiHG + CI1C13 = CH(C(;II,)., + slid.

Triphenylinethane.

Anthracene has been, synthesised from tetrabromethane and
benzene by this method,

I      Br ! CII ! Hr      !                             ,CIU

CVIL; 11.,    i !    ;    iio:c(iii4 = ctin/ i   X,c(in4 + 4iiBr.

'     ;     ~Hr ! CII    Ur    "i                             '

Anthracene.

(4)  Amides may be prepared by the use of chloroformamide,

CBH0 -I- CICONHo = CGHVCO.NH3 + ITC1.

The chloroformamide is obtained by passing HC1 gas over
heated cyanuric acid (Gattermann),

IIOCN + 1IC1 = Cl.CONIIo.

(5)   Hydroxyaldehydes have been obtained indirectly by -the
use of the crystalline compound HCI.HCN (which hydrochloric
acid forms with hydrocyanic acid) acting upon a phenol ether,

Cfln,OCH8 + HCI.HCN =

/OCH3
SCH:NH.

The aldime is subsequently hydrolysed  with dilute sulphuric
acid (Gattermann),

H20   =   C0H4<
\

NIL,

COH

In   addition  to  the   Friedel-Crafts' reaction,   the  aromatic
ketones may be obtained by distilling the calcium salt of the
APPENDIX

aromatic acid or a mixture of the salts of an aromatic and
aliphatic acid. The reaction is precisely analogous to the
process used for the preparation of aliphatic ketones,

2C0HaCOOca' = CGHaCO.CeHa + CaCCX

Benzophenone.

C8HaCOOca' + CII3COOca' - C6ITS.CO.CH«  + CaCO,.

Acetophenone.

They possess the usual properties of ketones of the aliphatic
series (see p. 69), which are illustrated by the various reactions
described at the end of this preparation..

A special interest attaches to the oximes of those ketones
which contain two different radicals linked to the CO
group. Many of these substances exist in two isomeric
forms, which are readily converted into one another. Phenyl-
tolylketoxime exists in two forms and benzildioxime in three
forms, which cannot be explained by structural differences
of constitution. They must therefore represent different
space configurations of a type analogous to that of citra-
conic and mesaconic acid (Hantzsch, see p. 265). They
are distinguished by the terms " syn " and " anti," corresponding
to " cis " and " trans " among the unsaturated acids. " Anti "
signifies away from the group, the name of which follows ;
"syn" signifies the position near that group (see pp. 283 and

3°0»

CflIIa.C.CcH4.CH3                  CcHa.C.CBH4.CII3

HO.N                                         N.OH

J5>«-Phenyltolylketoxime.                  A »#-Phenyltolylketoxime.

Benzil forms three dioximes which are distinguished Sy the
names " syn," "anti," and "amphi."

I I,C. C. C0HB     CaHs. C - C. CGH5   CCH5, C ---- C. CQH5
HO.N N.OH         HO.N   HO.N                    N.OH HO.N

anti.                           amphi.                                         syn.

The action of PCL-, on these substances, known as Beckmann's
reaction, is of great importance in distinguishing the different


PRACTICAL ORGANIC CHEMISTRY

forms of ketoximes.      The two isomeric  phenyltolylketoximes
yield two different amides,

QH5. C. CGH4. CI I,     C8H0. C. C8H4CH3

HON

QHs.c.cflH4ciL

II       -»

NO II

Cl.N

OC.C6H4CHS
C6H5HN

Toluic anilide.

CfiIIfi.C.C«H4.CI-I,   CuHaCO

II        ->              I

N.C1                      NIICJI4CIT,

Renxoic toluidc.

Toluic anilide, on hydrolysis, forms toluic acid and aniline,
whereas benzoic toluide yields benzoic acid and toluidine. It
follows therefore that, in the original compound, the first con-
tains the hydroxyl nearer the phenyl group and the second
nearer the tolyl group.

For further details on the stereoisomerism of nitrogen com-
pounds, the text-book must be consulted.



PREPARATION 101.
Diphenylmethane.—This reaction is analogous to that of
aluminium chloride on a mixture of benzene and benzyl chloride
referred to in the notes on Prep. TOO, p. 310. The reaction is
also effected by the use of zinc dust or finely-divided copper
(Zincke).
PREPARATION 102.
Triphenylmethane.--This is another example of the
" Friedel-Crafts'" reaction, which has already been referred to
in the notes on Prep. 100, p. 309.
Thfc synthesis of pararosaniline from triphenylmethane is one
which has gone far to solve the problem of the constitution of
the important class of triphenylmethane colouring matters.
Rosaniline or magenta was originally obtained by oxidising
with arsenic acid a mixture of aniline with o- and p-
toluidine. The product was then lixiviated and treated with
common salt, which converted the arsenate into the hydro-
chloride of rosaniline. Pararosaniline was prepared in a similar
way from a mixture of aniline and /-toluidine. The series
APPENDIX

of reactions by which triphenylmethane is converted into para-
rosaniline may be represented as follows : —

C8H5            /CJ-T4NOo            /C«H4NH0            /CGH4NH.,

C«H0 -> UC(- C6H4NO.", -> HC(-C6H4NH,; (HO)C(-C6H4NH;

Triphenylmethane.   Trin;;rethanPehenyl"     • Paraleucaniline.           Pararo^niline

By the action of hydrochloric acid on the base, the hydro-
chloride of pararosaniline is formed, which is the soluble'
colouring matter,

HO.C(G;ll4NIT2)o + IIC1 = C(Ct!TI4NHo):>Cl H- H2O.

The constitution of the hydrochloride is doubtful ; but the
so-called quinonoid structure, by which the substance is repre-
sented as a derivative of quinone, is generally accepted,

C(C,H4NH.,)o
II

C

/\
ITC/         ^CII

'Gil



NIT. TIG.

Pavavosauiline hydrochloride.

The formation of rosaniline from a mixture of aniline, o- and
//-toluidine is represented by assuming that the methyl-group
of /-toluidine acts as the link which connects the nuclei of
aniline and ^-toluidine.

IIC ill II     C(5lI4NUo    +  30  =   HO-C^C6H4NHa   +  2H,O

Rosaniline base.

PREPARATION 103.
Benzaldehyde    Green.—-The    formation   of   malachite
gre^n  (benzaldehyde   green) by the action   of  benzaldehyde
3*4

PRACTICAL ORGANIC CHEMISTRY

upon dimethylaniline in presence of zinc chloride, and subse-
quent oxidation of the product, may be interpreted on similiar
lines, and has already been referred to. (See notes on Prep. 59, p.
279).

xC6H5

l^""H\ CCH4N(CH3)2
••.°    HjC(iH4N(CH3)2

/C6H5       -
HCf-Q;II4N(CH,)o"

\cfiii4N(cii;).>

/C6H5

HC~-QH4N(CH3)2
\C(;H4N(C1L).2

Leukobase of
malachite green.

X:8IIfi
O  =   IIO.C~C(;II4N(CII,)o

P>ase of malachite
green.

The preparation of " crystal violet" from Michler's compound
and dimethylaniline in presence of POCL may be explained in a
similar fashion,

nr XC(;II4N(CII,)o                  Xy-I4N(CIIs)o

UL\Q5II4N(CH,)o   =  IIO.C^CGH4N(CII,).,

+ HCGH4N(C'IL)2               \C(iH4N(CIL>)o

Base of crystal
violet.

The constitution of thehydrochlorides of malachite green and
crystal violet will appear as follows : —

C/C«II5
 \r\CdlI4N(CIL),
	r/C,,H4N(CHs)2
 ^•CV.U.NICH,),

C
	yv

x\
 IIC/       ^CII                                PIC
	x Yn

IIC^        /Cll                              IIC
	\ /cn

\/
	\/

c
	c

N(CH3)2
	N(CH3)2

1
	1

Ci
	Cl

Malachite green.                                            Crystal violet.
	
PREPARATION 104,
Phthalic Acid.    In the formation of phthallc acid by the
oxidation of naphthalene with sulphuric acid, the mercuric ^ul-
AI'l'KNDIX                                    315

phate acts as a catalyst. The latter reagent has been used success-
fully in other oxidising processes, although the manner of its
action is not yet explained. The formation of phthalic acid from
naphthalene represents the initial stage in the manufacture of
artificial indigo from coal-tar. The subsequent processes consist
in converting the acid into the anhydride by sublimation., the
anhydride: into phthalimide by the action of ammonia yas, and the
phthalimide into anthranilic acid by the action of sodium hypo-
bromite (Hofinann's reaction, see p. 80).

co-.                  /CON m:r

Nil -> CV.1I/                ->

Co                        X'OOIl

NIL,

The anthranilic acid is then converted into indigo by
combining it with ehloracetie acid and fusing the product with
caustic alkali, which gives indoxyl and finally indigo by oxida-
tion,

.N'll.,                                            /NIICIUCOOII

•i ciciL.cooii - tyi/

"             '    ' coon

,NIk

PRKPA RATIONS 105 and 106.
Naphthalenesulphonate of Sodium. /3-Naphthol.-—
The formation of the sulphonic acid of naphthalene and the
corresponding phenol by fusion with caustic soda is analogous
to that of ben/.ene sulphonic acid and phenol (see Prep. 74,
p. 177,111x176, p. 179. It should be noted that naphthalene
forms two series of mono-derivatives distinguished as a and ft
compounds. By the action of sulphuric acid on naphthalene,
both (i and # sulphonic acids are formed. At a lower tempera-
ture (100 ) the product consists mainly of the a compound ; at a
3i6

PRACTICAL ORGANIC CHEMISTRY

higher temperature (170°) of the {3 compound. /3-Naphthol and
its derivatives are used for the preparation of azo-colours (see
Reaction 6, p. 163), and for that of/3-naphthylamine. The latter
is obtained by the action of ammonia under pressure on #-
naphthol,

C10H7OH + NH3 = C10H7NH2 + H2O.

This reaction is resorted to for the reason that naphthalene
forms only the a-nitro-compound with nitric acid. The method,
similar to that used for preparing' aniline from nitrobenzene,
cannot, therefore, be employed for the production of #-naphthyl-
amine. a-Naphthol is mainly used for the manufacture of
yellow and orange colours (Marti us and naphthol yellow) by
the action of nitric acid, and are similar in constitution to picric
acid (see Prep. 107).

The naphthols differ from the phenols of the benzene series
in forming ethers after the manner of aliphatic alcohols, viz., by
the action of sulphuric acid on a mixture of the naphthol and the
alcohol, which the other phenols do not,

C10H7OH -f CHaOH = C10H7OCH, -I- H3O

Naphthyl methyl ether.

PREPARATION 108.

Anthraquinone.— The constitution of anthraqninone is
derived from various syntheses, such as the action of zinc dust
on a mixture of phthalyl chloride and benzene, or by heating
benzoyl benzoic acid with PL>O5,

,COCl                         /OX

I4 -I- 2HCI

C;H

Nx-

-coon

= QH/       ,v

XXK

4\co

:«ir4 -i-

Unlike benzoquinone, it is not reduced by sulphur dioxide
(see Prep. 85, p. 193). Heated with HI or 'zinc dust it is con-
verted into anthracene.
PREPARATION no.
Alizarin. — The first synthesis of alizarin is due to Graebe
and Liebermann (1868). The present method was discovered
simultaneously by these chemists and by Perkin. By the action
APPENDIX

317

of fuming sulphuric acid on anlhraquinone, the main product is
^-anthraquinone monostilphonic acid.

By fusion oi the sodium salt with caustic soda and potassium
chlorate, the hyclroxyl groups enter the a and (3 position. The
constitution of alizarin is therefore

Oil

Oil

Alizarin.

The constitution has been determined by its synthesis from
phthalic anhydride and catechol in presence of concentrated
sulphuric acid (Baeyer),

/OH    i             /CO,          /OH    i

:BH/           = C6H/      >C6H,/

NDH  2           xx)/       x)n  2

Other colouring matters have been obtained by the oxidation of
alizarin (purpurin), and by fusion of the disulphonic acids of
anthraquinone with caustic soda (anthrapurpurin and flavo-
purpurin). It is an interesting fact that, among the numerous di-
and poly-hydroxyanthraqui nones, only those which have the two
hydroxyls in the aft position are colouring matters (Liebermann
and Kostanecki),

/co\

Oil

OH

uo/

/CO,

on

; OH

OH

Purpuvin.

no

Anthrapurpurin.

OH
[OH

\/\CQ/\/
Flavupurpurin^
PRACTICAL ORGANIC CHEMISTRY

PREPARATION in.

Isatin.—The   formation   of   isatin   from   indigo   may  be
represented as follows :—

/CO,

O   ; O

Indigo.

/CO ,
<X      ^>CO.

Pscudo-isatin.

This compound represents the unstable psetido- or lactam-
form, and passes into the stable or lactim-form (Baeyer),

-CO.

Isatin (stable form).

There exists, however, some uncertainty as to which formula
represents the stable form. Derivatives of both forms are
known, and the compound offers an example of iautomcrism
(see Notes on Preps. 16, p. 252), or, as it has been also termed,
pscudomerism*

The constitution of isatin has been determined by its synthesis
from ^-nitrophenylglyoxylic acid,

CBH4<

/CO.COOH

/CO.COOH

Q,H4

/CO,

I
f

iiii

which passes on reduction into the amino-compound, the latter
forming the anhydride or isatin (Claisen).

PREPARATION 112.
Quinoline.—The formation of quinoline by "Skuaup's
reaction" may be explained as follows : The sulphuric acid
converts the glycerol into acrolein, which then combines with
the aniline to form acrolein-aniline. The latter on oxidation
with nitrobenzene yields quinoline.                                      "»
APPENDIX

319

CIUm.CII.OII.ClI.jOII = CII.j:CTI.COII + 2H.,O

Acrolein.

HrjNIL -|- OCIl.CIIiCIIa = C,jIl,N:CH.CH : C1L> + II2O

Acrolcin aniline.

CII
I
CM

IL.O.

N

Quinolinc.

The reaction is a very general one, and most of the primary
aromatic amines and their derivatives can be converted into
quinolinc derivatives, provided that one ortho-position to the
ami no-group is free. 0-Aminophenol, for example, yields
^-hyclroxyquinolinc in the same way,

/\

0-Ainiuophcnol.

\/\/

on N

0-Hydroxyquinoline.

PREPARATION 113.
Quinine Sulphate.—Quinine belongs to the group of
"vegetable bases" or alkaloids. These substances are widely
distributee' among' different orders of plants, and are usually
colourless, odourless, and crystalline solids. A few, however,
are liquids (coninc and nicotine), and possess an unpleasant
smell. There is no general method by which the alkaloids can
be isolated from the plants in which they are found. They
usually exist in combination with acids, such as malic, lactic,
and other common vegetable acids. Frequently the acid present
is peculiar to the plant in which it occurs. Quinine and the
other cinchona alkaloids are found in combination with quinic
arid, morphine with meconic acid, aconitine with aconitic
acid, &c. A common method for separating the alkaloid is to
add an alkali. If the base is volatile in steam, like conine, it
is distilled with water ; if, as generally happens, the substance
is iron-volatile, it is extracted by means of a suitable volatile
PRACTICAL ORGANIC CHEMISTRY

solvent, such as ether, chloroform, alcohol, amyl alcohol, £c.
The solvent is then distilled off, and the alkaloid, which remains,
is either crystallised or converted into a crystalline salt.

The alkaloids are strong bases, which turn red litmus blue, and
are very slightly soluble in water. They form soluble salts and
double salts with platinic and auric chlorides. The principal
general reagents for the alkaloids are :

1.  A solution of iodine in potassium iodide, which forms a
reddish-brown precipitate of the periodides.

2.  A solution of phosphomolybdic acid in nitric acid, which
gives yellow precipitates of different shades.

3.  A solution of potassium mercuric iodide, which forms white
or yellowish-white precipitates.

The constitution of quinine is not yet elucidated. Its relation-
ship to quinoline has long been known, since it gives this
substance on distillation with caustic potash (Gerhardt).

PREPARATION 114.

Phenylmethyltriazole Carboxylic Acid.-—The mother
substance of this compound is a triazole, viz., pyrro-a/3-diazole,
which is one of four isomeric compounds :

NH                  NH                    NH                     NH

N/\N        N/^CH        N/\CH        HC/Vli

UC-—^CH         N'J—LCI!          HC!—L'N-                N----L'N

Pyrro-act'-diaicole.    Pyrro-ajS-diazole.         Pyrro-a/3'-diuzole.        Pyrro-jS/J'-cliazule.

Pyrro-tt/3-diazole was first obtained by the oxidation of azimido-
toluene, which in turn was prepared by the action of nitrous
acid on 0-toluylenediamine,

CH3

Azimidotoluene.

HQ.OC\/

HOOC.C/XN

HOOC.C

Aximidobenzoic acid.           Triazoledicarboxj'lic acid

HC

iid

/\

Pyrro-a^-dia/jolc.
APPENDIX

It is a colourless oil, b. p. 28o'J, with the properties of a weak
secondary base, dissolving in acids, and forming easily hydro-
lysable salts.

The reaction described in this preparation is of a general
character, and'furnishes a useful method for preparing members
of thrs series of heterocyclic compounds. Diazobenzolimide
condenses in a similar fashion with ketones (acetophenone) and
dibasic esters (malonic. ester) as well as with ketonic esters, as in
the present case. These substances possess the usual properties of
cyclic compounds ; carboxyl may be removed as CO.,, and alkyl
side-chains oxidised to carboxyl ; they may be stilphonated and
nitrated, and the nitro-group reduced to an ami no-group ; the
phenyl group attached to the nitrogen may also be removed by
oxidation. Thus, phenylmethyltriazole carboxylic acid loses
CCX on heating, and on oxidation the methyl group becomes
carboxyl and can also be removed in the same way. The
resulting product is phenyl triazole. The properties of the
individual triazoles are influenced, like other cyclic compounds,
by the groups attached to the nucleus, and to some extent also by
the basic character of the mother substance.

COHEN'S ADV. P. o. c.
322

PRACTICAL ORGANIC CHEMISTRY'

HINTS   ON    THE    INVESTIGATION    OF   ORGANIC
SUBSTANCES

Provide yourself with a good book of reference, or chemist's

pocket book which contains tables of physical constants.

Homogeneity. — Determine if thesubstanceishomogeneous.

A Liquid. — If it is a liquid, distil a few c.c. from a miniature

distilling flask with a long side-tube, but no condenser, or with

the apparatus shown in
Fig. 86, in which the con-
densing surface is sup-
plied by an inner tube
through which water per-
colates.1

Use a thermometer and
collect the distillate in a
test-tube. Note the boil-
ing-point, and observe if
it fluctuates or remains
constant and if any solid
residue remains. A low
boiling - point generally
denotes a low molecular
weight. A portion dis-
tilling in the neighbour-
hood of 100° may indicate
the presence of water.

It is useful to shake a
known volume (5 c.c.) of
the liquid with an equal
volume of water and to
note if the substance dissolves, or if any marked change in the
volume of the liquid occurs. A convenient apparatus for this

FIG. 86.

This a

If the side pie

pparatus can also be used as reflux condenser or for collecting evolveti gas
piece is furnished with a delivery tube dipping under water or mCrcury.
APPENDIX

FIG. 87.

purpose is shown in Fig. 87, which is merely a small and narrow,
graduated cylinder holding 10 c.c.1    The solubility of a portion
of the liquid is an indication  of the  presence of a
mixture.    Furthermore, the specific gravity of the in-       A
soluble portion (its floating or sinking in the water)     *&
will be roughly indicated and should be noted.
A Solid.—If the substance is a solid, examine a
few particles on a slide under the microscope, or,
better still, recrystallise a little if possible and notice
if the crystals appear similar in shape. If it is a
mixture, try to separate the constituents by making a
few trials with different solvents, water, alcohol, ether,
benzene, petroleum spirit, ethyl acetate, acetic acid, etc.
If it appears homogeneous, determine the melting-
point, the sharpness of which will be a further con-
firmation. If it turns out to be a mixture, it must
be further treated in the manner described under
" mixtures " (p. 343).
The Action of Heat.—We will assume in the first
place that the substance is homogeneous and consists
of a single individual. Heat a portion on platinum foil and
notice if it volatilises, chars, or burns with a clear, luminous,
non-luminous (aliphatic), or smoky (aromatic) flame. Determine
the nature of the residue, if any? when the carbon has burnt
away.
Metalor metallic oxide or carbonate may indicate the presence
of an organic acid, phenate, or double salt of a base.
Sulphate^ sulphite, or sulphide may indicate a sulphate,
sulphonate, mercaptan, or bisulphite compound of an aldehyde
or ketone.
Cyanide may indicate a cyanide or ferrocyanicle, etc.
Heat a little of the substance in a small, hard-glass tube and
observe whether the substance melts, chars, explodes, sublimes,
or volatilises ; whether an inflammable gas, water, etc., is evolved ;
also notice the smell.
Carbohydrates, polyhydric alcohols, higher organic acids (e.g.>
stearic), dibasic and hydroxy-acicls (^., tartaric), certain amides
(e.g.) oxamide), alkaloids, and azo and other organic colours char
1 Both pieces of apparatus (Figs. 86 and 87) can be obtained from Mr. O. Baum-
bach, %, Lime Grove, Oxford Street, Manchester.
Y 2
324

PRACTICAL ORGANIC CHEMISTRY

I
•f

dt i

and give off water or (if nitrogen is present) ammonia or basic
constituents. But a great number of common organic com-
pounds are volatile without decomposition.
The Elements.—Test for nitrogen,1 sulphur, and halogens. If
none of these are found, carbon and hydrogen are present and, if
the substance has given off water or is soluble in water, it may
be assumed that oxygen is present as well. The action of sodium
on the substance, if liquid, or on its solution in benzene orligroin,
if solid, should be tried in the apparatus, Fig. 86, and the gas
evolved ' tested for hydrogen, which if present, may indicate
hydroxyl, ketone, or ester groups.
The presence of nitrogen may indicate an ammonium salt,
organic base (aniinc or alkaloid], amino-acid, amide, cyanide,
\sotyanide, oxime, nitroso- or nitro-compound, azo-compound, etc.
The presence of sulphur may indicate a sulphate of an organic
base, alky I sulphate, sulphite, sulphide, tnercaptan, sulphonic acid,
bisulphite compound of aldehyde or ketone.
The presence of a halogen may indicate a haloid salt of a
base, alky-l, alkylene, or aryl haiide, add haiide, haloid derivative
of an. aldehyde or acid. Some substances, like mustard oils,
amino-sitlphonic acids and thioamides, contain both nitrogen
and sulphur.
Solubility.—Try if the substance dissolves in hot or cold
water. Apart from the salts of organic bases and acids, many of
which are very soluble in water, the solubility of simple organic
substances is generally determined by the presence of the OH
group (including CO.OH and SO2.OH groups) and to some
extent by the NH2 group. The greater the proportion of OH
groups to carbon, the greater, as a rule, is the solubility in water.
The lower alcohols, methyl, ethyl and propyl alcohols, are
miscible with water; normal butyl and wvbutyl alcohols (fermenta-
tion) dissolve in about 10 parts of water at the ordinary tempera-
ture ; amyl alcohol (fermentation) in about 40 parts of water, The
first two may be separated from solution by the addition of solid
potassium carbonate. The addition of common salt is sufficient to
1 It is sometimes difficult to detect nitrogen by the sodium test. The result should
not be regarded as conclusive, especially if the substance is volatile, unless it has
been dropped in small quantities at a time into the melted metal, which should _be
heated in a hard-glass tube clamped in a retort-stand. Special care must be used with
mtro-compounds, which may explode and shatter the tube.                               •»
APPENDIX

325

separate- the last three (propyl, butyl, and amyl). The poly-
h yd ric alcohols,glycol,glycerol, and mannitol, and also substances
like the sugars are extremely soluble, for the proportion of OH
groups to rarbon is high. Ordinary phenol requires for solution
i 5 parts of water, whereas the di- and tri-hydric phenols readily
dissolve. The same applies to acids. The lower monobasic
aliphatic acids (formic, acetic, propionic, and normal butyric)
are easily soluble in water, whereas /.wbutyric requires 3 parts
and valeric about 30 parts of water. The last three separate
from watrr on the addition of salt. The dibasic and hydroxy-
ac'uls, ^'herr the proportion of carbon is small (succinic, tartaric,
and citric-, are naturally more soluble than the monobasic
arids having ihc same number of carbon atoms.
The majority of aromatic acids are not very soluble in water
at thr ordinary temperature, for the proportion of carbon to
carboxy! is high ; the hydroxy- and polybasic and also amino-
acids arc more soluble than the unsubstituted monobasic acids
; or, if substituted, where thr substituents are halogens or nitro-
-..M'oups, which diminish, as a rule, the solubility). One thousand
parts of water dissolve about 2l> parts of ben/.oic, 2\ parts of
-uilicylic, tS parts of phlhalic, and 159 parts of mandelic acid.
A< ids Mich as gallic and tannic acids are readily soluble in water.
Thr sulphonir acids and also many of their salts are very
soluble.
Thr lowrr aliphatic amines and amides are soluble in water,
but not thr higher members, nor the simple aromatic amines ;
but some diainines, ammo-phenols and ami no-acids are moder-
ately soluble. Many of these soluble compounds may be
extracted with ether after salting-out (adding common salt to
.saturation). If the substance is soluble in water," it maybe one
of thr abo\e-named compounds, or a lower aldehyde or kelone,
or a bisulphite compound of these substances, or the salt of a
base or acid.
Tin- following is a list of the more soluble organic compounds
their boiling-points, melting-points and solubilities, which are
roughly indicated by the letters .v. (soluble in cold water) 7/..9.
f'Uaublr in hot water;.
326

PRACTICAL ORGANIC CHEMISTRY

SOLUBLE LIQUIDS AND SOLIDS.

Soluble.

A kohols—

Methyl (p. 67)...............

Ethyl (p. 49)...............

?z-Propyl.................

i-     ,,      ..................

«-Butyl..................

Ally!'(p. 'nog)'   '.'.'.'.'.'.'.'.'.'.'.'.'.'.'.

.     Benzyl (p. 195)..............

Glycol     ..................

Glycerol (p. 106).............

Aldehydes—

'•        Formaldehyde...............

Acetaldehyde (p. 64)...........

,,           ammonia...........

:       Chloral..................

Chloral hydrate (p. 99)...........

;       Butyl chloral hydrate...........

Acrolein..................

Ke/mies—

Acetone (p. 69)..............

Methyl ethyl ketone............

Bisulphite compounds of aldehydes and ketones

Ac Ms— _

Formic (p. 106)..............

Acetic (p. 74)...............

Propionic.................

w-Btityric (p. 98)..............

/-       ,,        .................j         j,

Chloracetic (p. 87)............;         ,,

Uichloracetic...............|         ,,

Trichloracetic (p. 99)............!         ,,

Bromacetic (p. 89).............j         ,,

Aminoacetic (Glycocoll) (p. 90).......i         ,,

Aminpcaproic (Leucine) (p. 133)......!      Ji.s.

Acrylic..................|         s.

Glycpllic(p. 102)..............i         ,,

Lactic...................;         ,, .

Glyoxylic acid (p.  102)..........     !         ,,

Pyruvic (p.  124)..............i

Oxalic (p. 100) (anhydrous)........

Malonic (p. 97)............

Kthyl malonic...............

Succinic (p. 113).............

Malic (p. 112)..............

Tartaric (p. 114).............

Citric (p.  124)..............

Citracpnic (p.  125)............

Benzole (p. 302).............

0-Chlorobenzoic.............

tJ-Flromobenzoic.............

Melting-     Boiling-  j
point.          point,    j

decomp.

57

decomp.

62

50
"'66

JO

So

66

78

97

&5

117

108

97
207
197

2QO

96

97
decomp.

52

56

Si

140
l63

155

186
190
195

208

140        i
decomp.   j

der.omp.

'6Ji    i

decomp.  j

0         11  forms   ) i

Iu°       jlanhyd. j!
decomp.  !

100

169
T54

122
137

!   anhyd.    ;
APPENDIX

327

SOLUBLE LIQUIDS ANT> Sftuns (continued}.

i
	Soluble.
	Meltiiij;-• point.
	Boiling-  j point.    •

Acids—                                                                       ' tf-Hydroxybenzoic (Salicylic) (p. ic.o)   ....
	h.s.    '
	155
	anhyd.

/-              „              ........   -               i
	"
	""
	

f-Aminobenzoic (Anthranilic) .....
	"
	
	


	"
	
	

p-              „              ........
	"
	187
	

(>• I OlUlC        .......               ...
	"
	
	

lit-    ,,      ............
	"
	
	

J>-      ,,     (p.   170)  .............
	"
	179
	

Gallic .   .• ..........   •  .      .      .     '
	"
	
	

Tannic           ....                                      '
	
	i . ,
	

Mandelic(p. 205)    ........... -.   . Benxilic (p. 20-1) ....   ..........
	h.".
	IIu
 I 50
	- .   ;

Cinnai)iic (p   204)   .              ....
	
	
	

Hydrocinniuuir (p. 204)    ....      .   .
	"
	.1.1
	

Phthalic (p   ^17)
	"
	21 '
	inliyd

Btjii/ene sulphonic (p.  177)   ........
	s.
	-1*
	

a-Naphthalene sulphonic  .....   .....
	
	QO
	

/3-         ,            (p. 218)         ...
	"
	
	

jS-Naphthol 6. sulphonic   ..........
	"
	125°
	

,,         6.8. disulphonicG ........ 3 6.           „         R .......
	M
	
	—


	h s
	decomn
	

A.lkyl acid sulphates (p  50)
	s.
	*
	


	h.s.
	126
	

Phenols—
	h.s.
	43
	t 1 i2r        I

Catechol           .............
	
	104
	24^

Resorcinol     ................
	
	1 13
	276


	"
	169
	subl.


	"
	
	

Canhvd \
	"
	107
	


	"
	132
	1

Phloroglucinol ...............
	h's.
	217 184
	suhl.

M       kt{     1
	
	95
	__

B-                  (n   "lo)
	
	122
	

Carbohydrate — Glucose (p.  1^5) ..............
	s.
	
	

Galactose  .................
	
	16}
	


	
	Q-
	,....

C'   i    sus?' r
	
	KIO
	._

i ' -,.   '.
	
	2O5
	

IM'iltost;              ...       ...........
	"
	
	


	1         11
	______
	

St '• »1
	i      h.s.
	______
	..._

Glucosides —
	1
	2OO
	

Arbutin                        •          ........
	h.s.
	J87
	


	
	17s*
	_._

c ]• -*
	
	20 1
	

«
	
	
	

I; -
ft*
i''
PRACTICAL ORGANIC CHEMISTRY

SOLUBLE LIQUIDS AND SOLIDS (continued}.


	Soluble.
	Melting-point.
	Boil in {j-point.

Bases — Methylamine (p   So)  .                             ....
	
	
	(Tin

JJimethylamine        .....
	
	
	

'Primethylamine  .   •
	"
	
	"

Kthylarnine   .....       .   .                  .   .
	"
	
	"

JJiethylamine    .......           .....
	"
	
	t^j

Urethane   ......
	"
	c^
	


	' '
	*
	Q ^

o- Phenylenediamine   .   .
	h s.
	TO°
	

«/-               ,,               (p- 155)   ........
	
	(> ] j j j
	-

yj-Aminophenol (p.  140)     ...
	"
	184
	

J-*yridine
	"
	
	116

Caffeine (p   1^1) •
	
	0 i4
	

Amides and Cyanides — Formamide   ....          .........
	s
	
	

Acetamide (p. 77)   ............. Urea (p.  i°6)    .......           .....
	
	82
 1 32
	P22

Thiourea (p.  128)    .............
	h.".
	T72
	' '

Succiniruide      .               .              .....
	
	T?6
	


	h.s
	
	

Konnanilide .   .
	
	46
	

Acetanilide (p.  151)    ...........
 Aretonitrile (p   79)
	»
	112
	_

Salts of bases and acids.
 Acid anhydrides and chlorides dissolve gradually on warming and yield the acid.
	
	
	

The above preliminary investigation will determine the further
course of investigation, but the following rough plan may serve
as a guide.
§ I. SINGLE SUBSTANCE SOLUBLE IN WATER :—
i. Contains only Carbon, Hydrogen and Oxygen.—
The number of such substances, as seen from the above table, is
comparatively small. It may be an alcohol, aldehyde or ketone
of low molecular weight, acid, phenol, carbohydrate or glitcoside.
Acids.—Make a solution (if not already dissolved) and test
with litmus. If the liquid is acid, a free acid\s probably present.
If the liquid is neutral and a metal has been found, a metallic
salt is probably present. If the liquid is alkaline, it may be the
alkaline salt of a phenol or an alkaline cyanide, both of which
are hydrolysed in solution. The separation and identification of
the acid is not a very simple matter. If the acid is an aromatic
APPENDIX

or an aliphatic acid of high molecular weight, in short, any acid
which either does not appear in the table or is marked as only                      •;
soluble in hot water, a few drops of cone, hydrochloric acid will                      ;
usually precipitate it, and it may then be filtered, or removed                      •
with ether, and its melting-point determined.    If no precipitate is
formed, but the solution turns brown on the addition of an alkali,                      ;
tannic or gallic acid may be present.     If the acid is volatile
and has a distinctive smell (formic, acetic, butyric, etc.), the
solution should] be acidified with sulphuric acid and distilled.
The  distillate will contain the free acid, which will probably
have a distinctive smell.   Individual tests may then be directly
applied,  but  it is  preferable to neutralise the distillate  with
caustic soda and evaporate to  dryness on the water-bath, so
as to obtain the sodium salt before testing.    The free acid may
be soluble and non-volatile, like oxalic, tartaric, succinic, citric,
etc., and then special tests must be applied (see tests for these                      :
acids).
Phenols.—If it is a free phenol, ether will extract it from its                     (
aqueous solution. If it is present in alkaline solution, the solution
should first be saturated with carbon dioxide. (N.B.—The alkaline
solutions of catechol, quinol and pyrogallol darken rapidly in
the air.) The following tests should then be applied.
Ferric chloride reaction.—Dissolve a drop of the free phenol                  1 *
in water and acid a drop of neutral ferric chloride.    A green                   1 '
(catechol),    blue    (orcinol,    pyrogallol)   or    purple    (phenol,                  Jj •
resorcinol) colouration is produced, which is often destroyed by
acid or alkali. Quinol is oxidised to quinone, and turns brown
(p. 193). The naphthols give precipitates of dinaphthol (p. 220).                      >
Schotlen-Baumann reaction (p. 209).—This may be applied to
the pure phenol in order to obtain thebenzoyl derivative, and the
melting-point determined, or the acetyl derivative may be pre-                     ^
pared by boiling for a minute with acetic anhydride with the                      ^
same object.
The action of bromine water (p. 180), Liebermann's nitroso-
reaction (p. 180) and the phenolphthalein reaction (p. 186), using
cone, sulphuric acid or zinc chloride, may also be applied.
Alcohols.—It may be a liquid alcohol (methyl, ethyl,
propyl, etc., glycerol, benzyl) or a solution of it in water. In the
former case its boiling-point will have already been determined.
Ittnay be further identified (i) by converting it into the benzole
330

PRACTICAL ORGANIC CHEMISTRY

1:

ester by the Schotten-Baumann reaction, and determining the
boiling-point or melting-point ; (2) by oxidation with excess of
bichromate mixture (10 grams of K2Cr2Or in 100 c.c. dilute
sulphuric acid, i : 3 by volume). The alcohols are boiled for some
time with reflux condenser, and the product distilled, neutralised
with alkali and evaporated on the water-bath and the sodium
salts tested. Glycerol will be identified by its viscid character
and reactions (p. 106). If the alcohol is in aqueous solution, it
should first be fractionated and potassium carbonate added to
the distillate, when the alcohol will separate. Glycerol or glycol
in aqueous solution may be separated by evaporation on the
water-bath.
Aldehydes and Ketones are detected in the first instance
by: (i) Shaking with a cold saturated solution of sodium
bisulphite (see Reaction 2, p. 67). (2) Adding to the aqueous
solution j#-bromo- or /-nitro-phenylhydrazine acetate solution
(see Reaction 2, p. 70).
The aldehyde may be distinguished from the ketone by its
reducing action on alkaline copper sulphate, ammonia-silver
nitrate and by SchifPs test (see Reactions, p. 67).
Carbohydrates will char on heating, and give off water and emit
a smell of burnt sugar. The substance is tested with alkaline
copper sulphate, ammonia-silver nitrate, phenylhydrazine acetate
or Molisch's test (seep. 136). Cane-sugar will not respond to
these reactions until it has been boiled for a few minutes with a
few drops of dilute sulphuric acid and inverted (see Prep, and
Notes). Special tests may then be applied to identify the
particular sugar. A few glucosides are soluble in water, and give
the sugar reactions after boiling with dilute acid.
2. Contains Nitrogen.—First test the original solid or
liquid by heating in a hard-glass tube with soda-lime (p. 2), and
notice if the smell is that of ammonia (ammonia salt, amide or
cyanide), an amine (amine or amino-acid) or a pyridine hase
(alkaloid).
Dissolve the substance in water, add caustic soda solution and
warm.
Ammonium or amine sa/fs, if present, emit the smell of
ammonia or amine ; if the salt of an insoluble organic base is
present (amine^ alkaloid)^ it may be precipitated as a liquid or
solid. Salts of aliphatic bases and bases such as benzylamjne
APPENDIX

33i

and pipenclitie are neutral ; salts of aromatic bases (ammo-
group in tlie nucleus) are acid. A soluble organic base (lower
amine, ben zylamine, pyridine) will be detected by its smell. Most
aromatic a. nil no-compounds and alkaloids are insoluble in water.
Some aromatic diamines and aminophenols are moderately
soluble. '-The nature of the amine, whether primary, secondary,
or tertiary, should then be investigated as described under § II.

of both the aliphatic and aromatic series will also
come under tliis head. Substances like glycocoll, alanine, etc., are
very soluble in water, giving neutral solutions, and may be
identified toy means of the copper salt (see p. 91). Ammo-acids
of the aliphatic series also evolve nitrogen when treated with
sodium nitrite and hydrochloric acid, and give off amines when
heated with soda-lime. Ammo-acids of the aromatic series
may be cliazotised and coupled with phenols, like aromatic
amines (see p. 151).
Amides and Cyanides. — Many amides and a few cyanides are
soluble iii water. They are decomposed by hot concentrated
aqueous or alcoholic caustic soda solutions, by concentrated
hydrochloric acid or sulphuric acid (equal vols. of acid and water)
on long reflux boiling. In the first case, ammonia is evolved ; in
the latter two case's, salts of ammonia are formed, which yield
ammonia on heating with excess of caustic soda. Anilides
behave si milarly, but aniline in place of ammonia is liberated and
must be looked for. Some amides are difficult tohydrolyse with
any of tliese reagents. In such cases, gently heating with
a mixture of one volume of cone, sulphuric acid and two
volumes of ethyl alcohol will yield the ester of the acid and
ammonium sulphate. The ester can then be separated by
adding n. little water and extracting with ether, and can be hydro-
lysecl arid the organic acid identified (see p. 333), whilst the
aqueous solution, after driving off dissolved ether, will give the
smell of smimonia on warming with excess of alkali.
3. Contains Halogen. — It may be a halogen add (e.g.,
chloracetic acid) or its salt, or the hydrochloride of a base or
timino-tif~/rfi or a substituted aldehyde (chloral, butyl chloral).
If it is ct free halogen acid, the solution will have an acid reaction,
and the solution will remain clear on adding caustic soda. If it
is? the hydrochloride of a base, it will give a precipitate with
332

PRACTICAL ORGANIC CHEMISTRY

AgNOo, and the addition of caustic soda will cause the base to
separate (if insoluble) as solid or liquid, or, if the base is volatile,
will produce a strong ammoniacal smell. The further examination
of the base is the same as that described under § I, 2. Acid
chlorides are usually insoluble in water, but rapidly decompose,
and may pass into solution as the free acid, giving at the same
time free hydrochloric acid.
4. Contains Sulphur.-—It may be the sulphate of a base,
in which case the solution will give a precipitate with barium
chloride, and the process of examination is that described under
§ I, 2. Heat with dilute hydrochloric acid. The bisulphite
compound of an aldehyde or ketone will be decomposed and
sulphur dioxide evolved. An alkyl acid sulphate will also be
decomposed, and free sulphuric acid will be found in solution
(see Reaction, p. 54). Distil with dilute sulphuric acid, and
test the distillate for volatile aldehyde or ketone. /.-Bromo- and
/-nitro-phenylhydrazine are useful reagents (see § I, i). An
acid ester of sulphuric or sulphurous acid will also be decomposed
by dilute sulphuric acid, and the distillate may be tested for an
alcohol. If it is an aroinatic mlphonic acid, it may be distilled
in steam with the addition of cone, sulphuric acid, when
the hydrocarbon will distil (p. 292), or fused with caustic potash,
when the phenol will be obtained (p. 179). Thiourea will also
appear under this head, and should be looked for. Heat a little
of the substance to the melting-point for a minute, and test for
thiocyanate with KC1 and FeCl3.
§ "ll. SINGLE SUBSTANCES, INSOLUBLE OR
SLIGHTLYSOLUBLE IN HOT OR COLD WATER.—This
category includes the majority of organic compounds.
i. Contains only Carbon and Hydrogen, or Carbon,
Hydrogen, and Oxygen.
Liquids.—It may be a hydrocarbon (paraffin,olefine,aromatic)
higher alcohol (e.g.* amyl alcohol), aldehyde (e.g., benzaldehyde)
ketone (e.g., acetophenone) acid (e.g., valeric acid), ether', ester,
fihenol (e.g., carvacrol) phenol ether (e.g., an i sole).
Hydrocarbons.—The action of sodium when testing for the
elements wrll already have indicated the hydrocarbon by its
inertness. The immediate decolonisation of bromine water will
identify it as an unsaturated hydrocarbon. A paraffin may be
distinguished from an aromatic hydrocarbon by treating tlte
APPENDIX                                  333
liquid with a mixture of concentrated sulphuric and nitric acids,
(p. 142;. The product is then poured into water. If the product
.sinks as a yellow liquid or solid it is prohablya nitro-compound
and the original hydrocarbon is aromatic. If it floats unchanged
on the surface of the water, it is probably a paraffin. An
aromatic hydrocarbon also dissolves in fuming sulphuric acid on
warming and shaking and does not separate on pouring the
solution into water. A paraffin is unacted on and separates on
the surface. There is also a marked difference in the smell of
the two classes of hydrocarbons.
Higher Alcohols and Phenol.—The substance will react
with metallic sodium yielding hydrogen, with phosphorus
pentachloride giving HC1. It can be identified by its
boiling point and by the b.p. or m.p. of the benzoic ester (p. 208).
In the case of a phenol it will possess a phenolic smell and may
give a, distinctive colour reaction with FeCla (p. 180).
Aldehydes   and  Kc tones.— The  usual   tests    are   applied
(P- 33°)-
Acids.— The number of liquid, insoluble acids is very limited
and is confined to the aliphatic series. They possess distinctive
b.p.'s and smells and dissolve readily in a solution of sodium
carbonate.
Ethers and Phenol Ethers have usually a pleasant odour
and if the methyl or ethyl ether is present are decomposed on
heating with strong hydriodic acid. The evolved gas passed into
alcoholic silver nitrate will give a precipitate as in Zeisel's method
(p. 220).
Kstcrs possess a fruity smell and usually distil without
decomposition. Boil with reflux for 5 minutes on the water-bath
a few c.c. of the liquid with 3 to 4 volumes of a ten per cent, solu-
tion of caustic potash in methyl alcohol and pour into water.
Notice if the liquid dissolves and has lost the odour of the ester.
An ester will be completely hydrolysed, and if the alcohol is
soluble in water a clear solution will be obtained. If the alco-
hol is volatile and the solution neutralised with sulphuric acid
and evaporated on the water-bath, the alkali salt of the organic
acicl mixed with potassium sulphate will be left and the acid
may be"investigated as described under §1. If it is required to
ascertain the nature of the alcohol in the ester, hydrolysis must
\g effected with a strong aqueous solution of caustic potash
334

PRACTICAL ORGANIC CHEMISTRY

»*

(rKO-Hj3HLO). Then distil the liquid, vising a thermometer.
The alcohol, if volatile, will pass into the receiver, \vhilsl the
acid remains as the potassium salt in the vessel. The boiling
point will give some indication of the former. The distillate
should be fractionated and dehydrated with solid potassium
carbonate. Its -boiling-point and that of the bcnxoic ester is
then determined.

Glyccrides.—If the substance is a liquid fat or oil (/./•. non-
volatile, which decomposes on heating, turning brown and
evolving the smell of acrolein) then the hydrolysis is effected
with methyl-alcoholic potash as described. After hydrolysis, the
alcohol is driven off on the water-bath, the residue dissolved in
water, and the organic acid set free with hydrochloric acid. The
acid if solid is filtered, if liquid extracted with ether, or if soluble
and volatile (butyric acid) distilled and the remaining liquid
neutralised and evaporated to dryness. The ^lycerol is then
extracted with alcohol and the alcoholic solution evaporated on
the water-bath. The tests for glycerol may then !><• applied
(p. 106). The following is a table of common insoluble liquids
with their boiling-points and specific gravities. Where the
temperature is not indicated the specific gravity has been deter-
mined at o".

ORGANIC LIQUIDS, INSOLUULK IN WATKK.
(Containing C and II or C, II, and (>.)

J'tf't't il* f'flj/x —

'/ Ikx'im-      '   Present    in    I'etroi;  IViml-   f

^Heptane     I    cum' I'^r.and  Lij-roi.i     *|

;/-Oi:t;ine       J                                           \

I'ctroleuiu (l:unp oil).....

/-Amyleiu:..........

Benxep.e (p.  136).......

Toluene (p.  163).......

Klhyl henxene (p.   141)    ....
fl-Xylene...........

duinene (Iso]>ropyl ben/cue) .   .

Pseuclocumene........

Mesitylonr.........

• •;•;(»;
i'HHo
o'Sf,-;
APPENDIX

ORGANIC LIQUIDS, INSOLUBLE IN WATER (continued}.-
			

	BoilJ"S- !   Sp. gr. point.    '      '   ta
		/.

Hydrocarbons (continued)--"                                     ! CymcMit:    .   .   .............
	'»   I
 155—160 || 60—165   |
 131 190 198
 206
 1
 124     !
 2129         : 179         I 237         ! 348         i 247 196
 ->5
 'J02
 -24
 176 '205
 138
 182 191
 2O2 2O2
 205
 236
 SJ8
 260
 35 176 42 104 154 172 232 232
 32
 57
	0-853 0-86=; - 0-870 o'Sso    , -0.861    '
 0'8l2
 o'S^o o-86S i '043
 0-990 0-897 1-045 0*983
 1 "122
 J'o49
 l'l22
 0*829
 1 '032 o'953
 0-947 0-945
 1-08
 1*070 1-037 1-033 i '033
 1"I2 0'gS5 1-09 I 'OS
 0-713
 o'Soo 0-850 0831
 0-988 0-973
 I"O22 I-JI4
 0'900 0-904
	i
 16
 !5        i
 20      :
 ,0           j 2O          ;
 'JO           :
 '-•0        :
 17 15
 15
 2O
 2O
 20            ,
 20      •
 ID 18 16
 15
 20 2O 2O
 *5
 20
 i
 2O

Turpentine oil (Pineuo)   .....
			
1 '«:moii oil (Liuiouenc)     .      •          ...      .
			
,'l/«»//0/.v —
			
Oclyl         .                                ........
			

			
I'eu/yl (p.   195) ..............
			
A Me/lyrics—
			
Cilrul                          .          .........
			

			
C'uininuUltihydo                         ........
			

			

			
SnlicyUiltlehydc (p   a 88)     .........
			
AVAW.V —
			

			
c. ?- ,^! lunon<:
			
Act'<tx~ /•V'llerir                                              .....
			

			
/ 1 n fiy<h vV/t'.s" —
			
Phenols —
			
p".       i                  V   ,         •M"')
			
o v^icsoi              v.   •! • j
			

			
.»>          \P-    J°4^   '       'r)   "gv .......
			
lU.U.lCOl          ^     -l-o
			
1 *           1
			
.   lSeno    ;:  •
			
Ethers find Phenol Etkcn—
			

			

			
iVictnyia
			
A,cetai   .
			
^(>i          1
			
i ncncioi      .   .
			
/vnet 10 c
			
Esters —
			

			

			
Jt
1 *'
I
J

I I'

li



I.

\    ,

336

PRACTICAL ORGANIC CHEMISTRY

ORGANIC LIQUIDS, INSOLUBLE IN WATER (tontinuctt).


	Boiling-point.
	Sp. gr              /.

Esff r.v (continued) — Methyl  propionate   ...
	79
	

butyrate   ............
	i i 7
	0*896             -o 0*870              "n

succinate      ...      .   .          .   .
	ip/l
	i Tar,               M

tart rate
	-So
	i '340               —

ben/oate      ...
	199
	i *o86              20


	''•'4
	1*18-7

Kthyl formate
	
	

acetate (p   81)  ..........
	77
	O 'gOO                         VI !

acetoacetate (p. 83) .........
	181
	

propionate  .   .....      .      ...
	99
	I'O29                          •")

butyrate
	
	0*896

/-valerate    .....
	1 TT
	n*88q               ••()


	186
	0*866               -jo

malonate (p. on) .
	198
	1*080                 "o


	
	I "076

tartrate (p. 115)    .......... benxoate (p   °oo)  .  .
	clecomp. °T3
	1*072                 —
 T '047        '             "O


	
	

wPropyl formate   .....
	Si
	o'qiS      ;         —


	7 r
	0*882

it-             acetate    ...
	
	0*885      :         -'0


	,,0
	0*901

utyrate .
	
	O'gn-,                      __

benzoate        ...
	n->\
	


	O7
	• 'oi'o     '


	g
	0*500              —

H-           acetate .........      .
	I o -
	

/-     ,      propionate   ............
	
	.go           !           __

,      butyrate   .      ...      ,      ...
	1 57
	o'&Sj


	160
	

/- A.n yl formate  ....
	
	0*880              °o

,     acetate      ......   ....
	1 39
	

propionate               .
	1 60
	0*887      '

butyrate    ......
	178
	

/-valerate  ............
	IQO
	0*870                  —

benzoate    ...
	
	

salicylate   .........
	O
	4

Glyceryl triacetate           .   .      .
	0=3
	


	
	


	JQ-
	^.yl^

Benzyl acetate       ...       .   .       .          .
	y-2
	.  ?"'

,,      benzoate (in. p. 20°)  .........
	323
	1*114       !          —

Solids.—It may be a hydrocarbon (e.g., paraffin wax,
naphthalene) higher alcohol (e.g.) cetyl alcohol); aldehyde (e.g.,
^-hydroxybenzaldehyde) ketone and quinone (e.g., benzo-
phenone, camphor) add (higher fatty, e.g., palmitic acid or
aromatic acid) ester (of glycerol, phenols or aromatic alcohols)
phenol (<?.£"., thymol),
The process of investigation is similar to that described in the
preceding section.                                                                  r
APPENDIX

337



I

Adds.—A free acid may be at once identified by its solubility
in a solution of sodium carbonate and by being reprecipitated
by concentrated hydrochloric acid. If a metal has been dis-
covered in the preliminary examination, a careful examination
must be made for an organic acid. As the substance is insoluble
in water the metal will probably not be an alkali metal. Boil
the substance with sodium carbonate solution. The sodium
salt of the acid passes into solution and the metallic carbonate
is precipitated. Filter ; boil the filtrate with a slight excess of
nitric acid, add excess of ammonia and boil until neutral, tests
may then be applied in order to identify one of the common
acids and the m.p. determined ; but beyond this it is impossible
to carry the investigation in a limited time.

INSOLUBLE SOLIDS.                                   ;

(Containing C and H, or C, H, and O.)


	Melting-point.
	
	Melting-point.    I

llydroca rbons — Paraffin wax ......
	45 — 60
	Acids — (continued) Anisic .........
	184        •

Naphthalene (p. ^16) .   .
	So
	<?-Toluic
	

Anthracene (p. 225)    .   .
	217
	
	1 jo

Phenanthrene   ....
	OQ
	jj.                 CQ     no)
	

Stilbene .  ......
	125
	Phenyl acetic   .....
	76

A Icohols —
 Cetyl Alcohol
	cjo
	0-Phthalio (p. 217) •  .   . I        tn-     „     (isophthalic    . if             (terephthalic)
	subl.

Menthol     .          ....
	42
	(p   171)
	"

A Idehydes — Vanillin
	Oj
	A nkydrides —
	4'j

Piperonal
	
	Phthalic(p. 218).   .  .   .
	i-S

Kc tones —
	
	Phenols — 0-Cresol         .      .
	

Benzil (p. 202) .....
	48 95
	/-    „     (p. 164)  .... Thymol .
	36


	*37
	a-Naphlhol   ......
	95

Quinones — • Benzoquinone (p. 192)   . o-Naphthaquihone .   .   . 0-            „                .-.
	116
 125 115 — 1 20
	£-       „        (p. 219)   .   .
 Esters—
 Methyl oxalate (p. 101) . Cetyl    palmitate   (Spermaceti)   .....
	J2'J
 54
 r-^

Anthraquinone (p. 225) .
	aC5
	Myricyl palmitate (Bees wax)   ......
	02 --- 65

Acids — Palmitic (p. 104) .... Stearic        .  .      ...
	205
 6-3
 69
	Glyceryl       "tripalmitate (Palmitin) (p. 104) . Glyceryl  _   tristearate (Stearin)
	62

Benxoie (p. 199)   .... tf-Hydroxybenzoic (p. 190) S      in-            .,             (p. 201)
 •^ /•      ;.
	155
 2OO 21O
	Phenyl benzoate .... ,,    " salicylate    .  .   . Benzyl benzoate   .... ,,      salicylate ....
	69
 43
 21

COHEN'S ADV. P. O. C.

i)
PRACTICAL ORGANIC CHEMISTRY

i

i

2. Contains Nitrogen.
Organic base.—If it is a base or amine, amino-phcnol or
amino-acid, it will probably dissolve in dilute hydrochloric acid
and yield a chloroplatinate with platinic chloride. Some
aromatic bases like diphenylamine are not very soluble in dilute
acids. Ammo-phenols and acids may be extracted with ether
from an acid solution to which ammonia has been added till
faintly acid and then sodium acetate. Many amines and
ammo-phenols give quinones on oxidation with potassium
bichromate and sulphuric acid having a characteristic smell
(p. 192). Many of the common alkaloids when dissolved in
hydrochloric acid (avoid excess) give a brown amorphous
precipitate with iodine solution and respond to other general
reactions for the alkaloids (see p. 320). To identify the
individual alkaloid, special tests must be applied.
Primary, secondary, and tertiary amines may be distinguished
as follows : To a solution of the base in dilute hydrochloric acid
add a few drops of sodium nitrite solution. In the case of
primary aliphatic amines, a rapid evolution of nitrogen will at
once occur; a primary aromatic amine at first gives a clear
solution of the diazonitim-salt, which evolves nitrogen and turns
darker on warming. The effervescence, due to the liberation of
nitrous fumes, is easily distinguished from that of nitrogen,
which goes on uninterruptedly, even when the liquid is removed
from the flame.
After the solution of the cliazonium salt has been decomposed
by warming, the phenol which has been produced may be
extracted with ether, the ether evaporated, and the phenol
identified by special tests. A solution of the diazonium salt,
when poured into a solution of/3-naphthol in caustic soda, will
usually give a red azo-colour. The original amine, if liquid, may
sometimes be identified by warming with a little acetyl chloride
and converting it into the solid, acetyl derivative, which is
recrystallisecl and the melting-point determined (see Reaction 3,
P. 76).
In the case of a secondary base, the above treatment with
hydrochloric acid and sodium nitrite will give an insoluble
nitrosamine (liquid or solid), which is frequently yellow. It may
be separatee! by ether and, after removing the ether, tested l*y
Liebermann's nitroso-reaction (see Reaction 3, p. 159). Nitrous
.acid has no action on tertiary aliphatic amines, but forms nitroso-
APPENDIX

bases with tertiary aromatic amines (see p. 157), which dissolve
in water in presence of hydrochloric acid, with which they form
soluble hydrochlorides. Tertiary amines also combine with
methyl iodide on warming (see Reaction, p. 157), but not with
acetyl chloride. Primary amines give the carbamine reaction
(p. 150), and unite with carbon bisulphide (p. 159).
Oximcs.—It should be remembered that oximes act as bases
as well as acids, and dissolve in both caustic alkalis and acids.
On reduction in acid solution (with tin or zinc) they yield"
amines.
Cyanides and Amides are hydrolysed by caustic potash
(aqueous or, better, alcoholic), cone, hydrochloric or sulphuric
acid as mentioned previously under § I, 2. It should be mentioned
that some amides are attacked only with difficulty, and must then
be treated as described under § I, 2.
Nitre-compounds are frequently yellow or orange in
colour. Heated with stannous chloride in cone. HCl or zinc
dust and glacial acetic acid they dissolve and remain in solution
on the addition of water. The base which is thus formed maybe
separated by adding an excess of caustic soda'until the metallic
oxide dissolves and then shaking out with ether. When the
ether is removed, the base remains. If liquid, the base should
be converted into the acetyl derivative by warming with acetyl
chloride for a few minutes and pouring into water. The free
base or solid acetyl. derivative, as the case may be, should be
recrystallised and the melting-point determined. It can also be
diazotised and coupled with p-naphthol.
Alky I Nitrates are hydrolysed like other esters, and yield
alcohol and nitric acid (p. 82).
Nitro-phenols and Nitro-adds dissolve in caustic alkalis
as a rule with a deep yellow or orange colour. On re-
duction with stannous chloride or zinc dust, as described
above, they yield the amino-derivatives. In the case of the
ammo-phenol, the solution is made alkaline with caustic soda,
saturated with CCX, salt added and extracted with ether. In
the case of the ainino-acid, the method used is that described
under Prep. 91 (p. 201).
Aso- and Azoxy-compounds. Both classes of compounds
r»re usually highly coloured and are rapidly decolorised by
winning with a solution of stannous chloride and hydrochloric
acid, forming amino-colnpounds (see Reactions, pp. I73> J77)-
L ORGANIC CIIKM tSTRY

INSGI.UHLK SUBSTANCKS.
(Containing (.', II, and N i»r C, II, ( ), and N.)


	Melting-   Boiling-
	
	IMcking-   Pioilin.cj


	point.   !   point. >
	
	j   point.      point.

/iast:s (primary)
	
	!   AHliHOfi/ltwh—
	1

AniHnc (ji.  140)   .   .
	tS'.-
	(     /-Aminophenol     (j
	.;


	71
	1                I.fl)>   ......
	1    i S.j

'A'-          ,,           (p.   l>()
	
	I      o-Melhylamino-
	

/•          ,,          (p.   1 r1 ))
	'•17
	phenot (Metul)
	,87

r'-Cldoianilini: .   .  V
	
	/-Mrthylamino-
	

»t-        ,,            ...
	•.-.jo
	ph(-i)ol(t>rtoD
	01 1

/•
	70            :•.;»
	!      ..!-.j-I )iaminopliciuil
	

c-ilromamline ...         ,;i            -'•.!
		;           (Amidol) .   .   .
	< leu imp.        —

/• H ydri >,\yaiiilinc(/-i

jiminophcnul)    . I    ii-'.|

Anisidiiit-.....;

a-Najihthylamine   . j       c-,<>

ft-        „           • i    "-•

Pjcnxidinc ()).   i.}!•') . ;    r.-.-

(p.   i?.i>  .   .   •   • ;
/-I>tmrlhyl|>lirnyl.
ciu'diaininc      (p.

•77)......

Clu-nylhydra/in.- (p.:

,

ISlHhylaniliiu: . . .
Kihyhujiline . . .
lic'H/ylaiiUtiM: . . .
1 >iplu.:iiyl;miin<: . .
Mcthyldiphcnyl-

ainiiic    .       ...
|      I'hcnyl /-{-luphtliyl-

/>Vr.v/w (tertiary)

I n'mrthylaiiilinc   (p.

nirlhylaiiiliui''   .   .

Dimethyl ^-t<»luidini;

a-Picoliiic.....

Ouinolim' (p.  ;:.;-.) .

.

licit/.ddchydt.' cy;in-
hydrin (p. -JDM) . ;
Ai'ctoxinu-    (p. 71)
<x-l>rn/aldo\iiiu;   (p.

;j     /3-Ben/.aldo\imc   (p.j

I      AiX'tophononcoxiim: j
.1           (p.  -.-it)   .   .   .     '

i ( 'vntt/./rx     and

;    "       .-/////f/.-.v                 I

:     Siuxinatm'dc    .   .   .

i      Ph.-nyl cyanide  .   . •
/>•'!'• >lyI cyanidi:   (p.

i"«»>      .....

().\aiuidc (p.  la.-)   .  (
lien/auiide.   (p. •'<>())
Hydnilicii/ainidc (p.i

4 »<;())......i

Salicylamide    .   .   . i

;     Konminilidt! .  .   .   .

I      Acctanilidc  (p.   •?;«).

!      Methyhlfetatiilide.     j

!      Pi'opionanilidc    .   . :

i      !5en/anilide   .   .   .   . !

j     Oxanilidc .   .   .   .   . |

I JiplienyluR-a    . •   • j
Tnphcnyl j;uanidiue
(p.  Kio)  .....

a«A<:etnap!ithaHdc .

M ipjniric acid .   .   .       i!-'>7
Unc acid   .....   d'-romp.
Anthranilic acid .   .       14.)

(P-  *54) •
APPENDIX

INSOLUBLE SUBSTANCES (continued}.


	Melting-point.
	Boiling-point.
	
	Melting-point.
	Boiling-; point, i

Nitro-compounds (continued). Tri nitrobenzene .   . 0-Nitrotoluene    .   .
 ™~              JJ                  •    •
 p-         .,,
 T -2-4-Dinitrotoluene a-Nitronaphthalene fl-Nitracetanilide P-           »     (P- T53)
 Nitro-phenohi  Aldehydes and Acids — <7-Nitrophenol(p. 183) ;//-           ,,            .   . P"            11       (p. 183) Trlmtvophenol    (p. 185)     .   .      .
	122
 54
 l\ 78 207
 45
 96 114
 T22
 53 T4S
 I4T. 23S
 179
 =05
	223
 230 238
	Nitroso-compounds — /-Nitrosodinrtethyl-aniline (p. 157)   . /-Nitrosodiethyl-aniline   ....
	35
 84
 10(1
 36
 63
 T2S 9S T27
	"   i
 1 6 S6 95 M7

			Nitroso-jS-naphthol
 Alky I  Nitrites   and Nitrates— Ethyl nitrite   .   .   . ,,     nitrate   .   .   . Aniyl nitrite (p. 69) ,,     nitrate   .  .  .
 ! Azo- and Azo.\-y-com-;        pounds — A/oxybenzene     (p. 143)   ......
		
Nitroanisole    .   .   . 77/-Nitrobenzalde-hyde .      ...
					
0-Nitrobenzoic acid jit*             , , (p. 200) ..... /-Nitrobenzene acid 1-2-4-Dinitrobenzoie a.cid       .....
					
			1     Axohenxene (p. 145) Hydrazobenxene fp.
 i46) .....:.
 Diaxoaininobenxene
 ;      (P.. i?0 .....
 Aminoaxobenxene 1        (P-  i?2> .....
		
r-vs-Dinitrobenxoic Virid    .....
					

					
3. Contains Halogen.—Halogen compounds may
alkylene, aryl or add halides or halogen acids (V.^-., ethyl loromide,
ethylene bromide, bromobenzene, benzoyl chloride, or chloro
benzoic acid).
Alkyl) Alkylene and Aryl Halides are usually liquids or
solids specifically heavier than water and with a sweet penetrating
smell, or if aromatic compounds substituted in the side-chain,
they have a sharp penetrating smell and attack the eyes. They
are for the most part colourless, but the bromine and iodine
compounds usually acquire a brown colour on standing. Iodo~
form is naturally yellow. In the case of alkyl and alkylene
halides and aromatic compounds substituted in the side-chain,
alcoholic silver nitrate will, on warming, yield silver halide.
Strong methyl-alcoholic potash will, with the same compounds,
produce olefines and acetylenes (p. 64). The experiment should
*» be tried with the apparatus Fig. 86, and the gas collected
ffij

342               PRACTICAL ORGANIC ("IIKMrsTkY

and tested. Aromatic compounds substituted in the nucleus
are not, as a rule, acted on by these reagents unless nitre-groups
are also present ; many of these react with magnesium in
presence of dry ether (p. 206).

I NSOU:1!I,K  SUIJSTA NTKS.
((Y>nifiinin£ (', II and halogens or (\ II, O uwl I

Ml   i                                     ..... -.- ..... - ................. •/ J|                                                                                    ;. \lellimv   r."iiiiu- ' i   i fi  '                                                                         i   point.       p»!nl.
 Jl                                 .                  ; -------- ;        -
*','                           ! -I//')'/, Alkvlw, and                  i               ! }*f|                           !        'Ant /'In/Mrs   •                                     ; 1   {'                          |     Methyl   iodide   (p. :                                ; j It                             '            nH)    ......                          ,)•;
	(r.nilinur.O                i                  ;
 /'-I >ibl«. ill, 'hell,'. -!,r  ,   ;         .:.)                .-i
 ;//            ,,             -   . ;                ;       'i

| I                              i      Kthy!   bromide   (p. \
 i i!                                     Kthyl iuilid.''   !   .   '. !                        7"      i u J [I                               1      w-l'iupyl chloride   . ;                        .(}       j
 I                        i,'     iod'idr '. ". i         '   »''•.•
 f     '                                   /-   ,,        chloride   . :                       -,'. »                                          „         bromide  . •                '      '•"
 j  1                                    W'l'.utyl rldoridr .   .                         77
 1 f                                  /-    ",'      chluridc"   1 i                     <'»•'•     ! 'fli                               i             i.       brnmidr     . !                 .      «.-.•      ' ill                         i                  i-li'l''    •  -! 1 1   I                            !     ;-Auiyl chloride  .   . i                ;    .....
 f                             i            „"    hro.uid,- .   . .•       -             ,,'..
 |                                   Ally! broniid.: '.   '.   '.                        -,-i      [
 1                               :      M.-iliylnn- i hh.iid.-                          ,| i
 If                              ••             ,,          bromide        • •              , :      :
 f,'                                    KihyliiU-ur"!, "    '.                  >       ,;      i 1                               i      Kthyleu.-    bn.midr                 |
 i.                               •     Kthylid'-ur bn)inid«'                 [    i<i> i                                i     Chloroform (p. 70} .                  j      M      i j                                     liromnfortu  ....        — -      !    «'ii I                                     loduionn .          .   .       i H>      !               i
	
	*!• M.-'    '.    .     ' .                    •             •-;., 'it-Mi- .'...'..           '..»       \      •    •
 Tji.h! ..... phrnul      ,        f/:     |
 '   '\..-(shl,|oiidr(p.V,i^                     \         ,
 . I, AA
 ,'-fhliiM,lM-M/«.ir   .    .  ;      I  V /•              ',',          '     .   .        :•!«'
 "w«-ihyl   fhtur..funn                ; ah*                                             ;      "i

\           *                          Cacliun KMvachlnride       —      i      7'' }|                                     1      JJiMl/yl  rhluildc   (p. 1        ^    »94> ......         —            '7^»
 J'fM»/()tnchl<tride    . .                  -.'i ; (Jllloniben/rnt;     .   .                         i ;;•
 ™                                    <?-! )ichl(>roljcn/(>iii< . ;       •       .    ijn
 Acid Chlorides and llrontid* than  water,   but reveal  their
	
	,,   "    hiouuurl.tte                            i', t
 v   are also sp«*rifi< ally  hravier presence   by  tuniinit   in   inoir.^
 «

APPENDIX

343

air. They are decomposed by water more or less rapidly,
and give the corresponding acid and hydrochloric acid, which
may be tested for. They are also acted on rapidly by strong
ammonia, and give the amide, the melting-point of which may
be ascertained (p. 209).

/Jti/w/i Acith and Esftrs.—Most of the insoluble halogen
acids belong to the aromatic series, and have a distinctive
meltim;~point. For further confirmation, they maybe converted
into the acid chloride and amide. Insoluble esters containing"
halogens may belong to both series, and the acid and alcohol
must then be separated and separately investigated.

4. The following among the more common organic substances
contain sulphur or sulphur and nitrogen in addition to carbon,
hydrogen and oxygen.

INSOLUBLE SITHSTANCKS.

Naphlhs laimii

nil; v  ,   1 1
	, ; i ii 1 1 r>
	( n  v »   li,  v ;,  n, iliui
	IN.;
	

Mrhinj-
.   point.
	Boilinj'.1 point.
	
	Melting-point.
	Boiling-point.


	I. JO
	77/iivwwrt^v--
	
	

,,,
	
	Allyi iluocyanatu .
	—
	151


	
	IJhcny\
	
	

;
	
	(p.  160) ....
	_-..
	300

1   drciiiiiji.
	
	
	
	


	
	'rhiocarbainidc  (p.
	1 7 ri
	


	
	'riiioairbaniiid'e (p.
	
	

.
	
	•59)    ...•"•
	151
	~

.
	-•
	uinide (p.  179)
	150
	_


	
	licu/nu'sulphonuni-
	
	

:' ~
	187
	iiilf (p.  i7<:>) .   .
	no
	

Mixturaa A preliminary investigation carried out as
ih-scribed on p. 322 will determine roughly if the substance is a
mixture. Before proceeding to identify the substances present,
it is essential that they should first be s^arated. This may be
a lonK and difficult operation, but the following methods may
lead to the desired result.
** If the :.ul.« taru'e cannot be satisfactorily separated by fractional
344

PRACTICAL ORGANIC CHEMISTRY

ti

1

distillation (if a liquid) or by crystallisation (if a solid), shake
with caustic soda solution. This will dissolve the acid or phenol,
and the insoluble constituent may be removed mechanically or,
if volatile, by distillation in steam, by extraction with ether or, if
solid, by filtration.
Acid and Phenol, if present together, may be separated by
adding sodium bicarbonate in excess and extracting with ether,
or by dissolving in caustic soda solution, saturating with carbon
dioxide and then extracting with ether. The ether extracts the
phenol, which is insoluble in sodium carbonate, leaving the acid.
Ester and Hydrocarbon may be separated by hydrolysis, which
decomposes the ester, but not the hydrocarbon.
Paraffin and Aromatic Hydrocarbon may be separated by the
action of fuming sulphuric acid, which forms the sulphonic acid
with the aromatic hydrocarbon. The product is poured into
water. The sulphonic acid dissolves readily in water, whereas
the paraffin is insoluble.
A mine or Base may be separated from the majority of
insoluble organic substances by shaking it with dilute hydro-
chloric acid, with which it forms the soluble hydrochloride.
Aldehyde or Ketone may be separated from the other
constituents by shaking the liquid, which should be free from
water, with a saturated solution of sodium bisulphite, and de-
canting or filtering the liquid residue. If the liquid is soluble
in water, like ethyl alcohol, it may precipitate the bisulphite of
sodium. This is prevented by adding a little ether before
introducing the bisulphite into the liquid.
In separating two liquids in a test-tube, for example, an
ethereal from an aqueous solution, either the ether may be
decanted or it may be desirable to withdraw the lower aqueous
layer. This is done by sucking the liquid into a small .pipette
furnished with a mouth-piece of rubber tubing, which may be
nipped when the requisite quantity is removed. The pipette is
then withdrawn, keeping the rubber tube tightly closed, and the
liquid transferred to another test-tube. It is often advisable to
adopt this method previous to decanting the top layer, which
is much more effectively separated from a small than from a
.large quantity of the aqueous layer.
APPENDIX

345

I.—TABLE OF THE ATOMIC WEIGHTS OF THE ELEMENTS.
O - 16.

Element.           ' Symbol. •
	Atomic  ! Weight. !'
	Element.
	Symbol.
 Ne.    i Ni.     : Nb. N. 0*. 0.
 pd.   ! p. pt.
 K.
 Ra. Rh. Kb. Ru. Sc. Se.
	Atomic Weight.

Aluminium     .  .   . :     Al.     | Antimony    ....       Sb.     | Argon   ....              Ar.     •
	27-1 j 120*2 i
 39*9    I J37'4
	Neon    ......
		20
 587 94 14-01 191 16 io6's
 194-8
 39-I5 225 103 85'5 101-7 44'r 79-2 28-4 107-93 23*05 S7'6
 •:j2 "06
 181
 127-6      i 204'!
 232-5
 no
 48-1 184 238-5
 5I -2
 128 173
 61-4
 90*6

		Nickel     ..... Niobium      .... Nitrogen     .... Osmium   .....
		
Arsenic    ..... •    As.      ! Barium                           Ba
				
Beryllium    .   .              Be.      !
		Oxygen    .....
		
Bismuth   ...      .       Bi.
	208 ii 79-96
 1 12 '4
 133 40-1
 140*25 35 '45  : 52-1
 %* l
 J9 .     1 70      !
 72*5    : i97'2    • 4-0 i-ooS
 "5 126-97
 193 55 '9 i33'9 206*9 8r8 7-03 24-36
 55 200 96
	Palladium   .... Phosphorus     .   .   . Platinum .....
		
Boron   ......        B. Bromine   ..... i     Br. Cadmium    ....       Cd. Caesium                        Cs
				
		Potassium   .... Radium   .....
		
Calcium   ...      .      Ca.
		Rhodium .    • .   .   . Rubidium    .... Ruthenium .... Scandium    .... Selenium
		
Carbon     .....        C. Cerium     .....       Ce. Chlorine   .   .   .              Cl.
				
Chromium   ....       Cr. Cobalt                             Co
				
		Silicon ......
	Si.
	
Copper ....              Cu.
		Silver   .   .   .   . •    . Sodium    .....
	AR.
 Na. S'r.
	
Fluorine                    i      B'
				
Ciillium                     :     ( i
		
		
Ciermaniuin     ...       Ge. (Jold     ...              An.
		Sulphur   ..... Tantalum    .... Tellurium    .... Thallium
	S. Ta. Te.
 Th. Sn. Ti. W. U. V. X. Yb. Y. Zn. Zr.
	
Helium    .   .  .             He.
				
Hydrogen   .....     H.
				
		Thorium .....
		
iodine                              1
		Tin    .......
		
Iridium            .               lr
		Titanium ..... Tungsten     .... Uranium      .... Vanadium   ....
		
Iron      ...            :     Ke.
				
Lanthanum    .   .   .       T..a. Lead     ......       Pb. Krypton   ....     !    Kr. 1 ithium                            Li
				
		Ytterbium   .... Yttrium   ..... !    Zinc ......
		
Magnesium    ...      Mg. Manganese ....      Mn. Mercury                   i    He;
				
		Zirconium   ....
		
Molybdenum ...      Mo.
				
346

PRACTICAL ORGANIC CHEMISTRY

VAPOUR TENSION OF WATER FROM 5° TO 20°.

t
	Tension.
	/
	Tension.
	t
	Tension.
	t
	Tension.


	
	
	
	
	
	
	

5-0
	6-507
	9-0
	3-543
	13-0
	11-137
	17-0
	M'395

T
	•552
	"i
	•606
	'i
	'210
	'i
	"480

'2
	"597
	•o
	•664
	*2
	'283
	'2
	•578

'3
 *4
	•643
 •689
	•3
	•722 •781
	'3
 '4
	•356 '430
	'3
 "4
	'670 '763

'5
	•736
	"5
	'840
	"5
	'505
	•^.
	'856

•6
	•782
	•6
	•899
	•6
	'580
	•6
	'950

'7
	"829
	*7
	'959
	•7
	•655
	•7
	1 5 '044

*8
	•876
	'S
	9-019
	'3
	'731
	'8
	•139

'9
	•924
	'9
	•079
	'9
	•S07
	•9
	'234

6-0
	•971
	IO"O
	•140
	14-0
	•884
	iS'a
	'330

•i
	7*020
	*i
	*2OI
	•i
	•96c
	•i
	•427

'2
	•068
	*2
	•262
	'2
	12-018
	*2
	'524

"3
	•117
	'3
	°3°4
	*3
	•116
	'3
	•621

'4
	•166
	"4
	•326
	"4
	•t94
	"4
	•719

*5
	•215
	"5
	'449
	'5
	"273
	"5
	'£18

•6
	"265
	•6
	
	•6
	
	•6
	•917

'7
	"314
	'7
	'575
	'7
	'4'>2
	'7
	16-017


	•365
	
	•639
	•3
	•512
	•8
	•117

*9
	"415
	"9
	'7°3
	'9
	'593
	'9
	"218

7-0
	•466
	ifo
	•767
	
	'674
	TQ'O
	'319

*i
	'517
	'i
	•832
	•i
	'755
	•i
	•421

"2
	•568
	*2
	•897
	'2
	•837
	'2
	'523

'3
	"020
	*3
	•962
	*3
	•920
	'3
	"626

"4
	"672
	*4
	T0'023
	*4
	13-003
	'4
	"7 3r->

'5
	'725
	"5
	•095
	'5
	'•086
	'5
	'814

•6
	'777
	•6
	*i6r
	•6
	•170
	•6
	'939

'7
	'830
	*7
	•228
	'7
	'254
	'7
	17-044

•3
	'883
	
	'296
	•3
	'339
	
	

'9
	"937
	"9
	•364
	'9
	•424
	•9
	'2^fl

8-0
	•991
	12*0
	"432
	i6'o
	•510
	20'0
	•3^3

•i
	3-045
	*I
	'SOT
	•i
	•596
	'I
	•471

'2
	'100
	*2
	'570
	"2
	•683
	'2
	'579

'3
	'T55
	'3
	•639
	'3
	•770
	"3
	•688

'4
	*2IO
	
	•709
	"4
	•858
	"4
	"797

*5
	-266
	"5
	•780
	'5
	•946
	'5
	•907

•6
	'32T
	-6
	•850
	•6
	
	•6
	1 8 'or 8

'7
	•378
	'7
	•921
	'7
	•124
	'7
	•129

•8
	"434
	*8
	'993
	• o
	•214
	•8
	"241

'9
	-491
	"9
	1 1 '065
	'9
	
	"9
	"353

APPENDIX

347

VAPOUR TENSION OF CAUSTIC POTASH SOLUTIONS FROM TO°—20°.

/
	-.oKOII. luoM-.O.
	4oKOH. looHoO.
	49KOH. looHoO.


	I
	
	


	
	
	

,<VO
	............ 7':u
	6^0
	5-62

J 1*1",
	ysr,
	6-72
	5'ui

I •<>
	7 'tiy
	6'Q5
	6*01

>"7
	8-19
	7-.-S
	6*29

.''i
	B-4i
	7'47
	6*^6

«'"cj
	S'fV?
	7-67
	6-61

J''*
	y *g«
	7'9J
	6'86

V5
	9'1?1!
	8-19
	7'og

.{"95
	y'4y
	S'44
	7 '?.o

4T>
	9^;>t
	8-74
	7'^

!> " i '"
	0'25
	q'li
	7-88

'"> " >' >
	
	9'ao
	7-96

i.r.)
	D*a-»
	9 "62
	8-33

fr »i-
	To;
	9-35
	3'53

7'<j
	''54
	O'i!6
	S-S8

/'"••
	I'yi
	o'S9
	9'i7


	'.•••. a»
	u-yj
	I                9 '47


	'.-•6u
	i -'.-9
	9-78

ij'i »
	:>"(ILJ
	1-65
	10*09

')'•}
	:5*4'
	i '93
	io'33


	.ry.",
	2 '40
	•              ^'75

-"'••""•
	4'iR
	'.•"';, o
	10*91

f

34^

PRACTICAL ORGANIC CHEMISTRY

II.—TABLE OF SPECIFIC GRAVITY AND PERCENTAGE OP SULPHURIC ACID
IN AQUEOUS SOLUTION.    (Kolbe.)

y/. £?-. at 15° comjxtred with ivaier at o° = T.

I

I
I

i

Degrees Keaume\
	,/=ig5/o.
	ioo parts by weight contain
	: Heaumc.
	SP- gr. ^=15/0.
	TOO parts by weigh i contain 'H.jSO4.

i
	"007
	1-9
	34
	•308
	40'2             !

i              2
	•014
	2'8
	35
	•320-
	41-6

;                       3
	'022
	3 '3
	36
	
	43

4
	'029
	4*8
	37
	'345
	44 '4

^
	•037
	5'8
	38
	'357
	45'6

6
	[045
	6'8
	39
	'370
	46-9

7
	
	7'3
	40
	'383
	43-3


	"060
	8-8
	4T
	'397
	4Q'8

Q
	'067
	9'8
	42
	•410
	5 '"a

IO
	'075
	io-3
	43
	'424
	5 -'•£">

ii
	"083
	TI"9
	44
	'43^
	54 '°

12
	'091
	T3
	45
	"453
	55 '4

i         T3
	*1OO
	14-1
	46
	•468
	56 '9

1         14
	•i 08
	15 "2
	• 47
	'483  -
	5*3' {

15
	•116
	16-2
	48
	"408
	59 "6

16
	'125
	1 7 '3
	49
	'5'4
	6t

17
	"134
	1-3 '5
	50
	'53»
	62-5

x8
	•142
	ig'6
	5r
	•540
	64

;        19
	"'5-
	20-8
	52
	'56*
	6^*5

20
	'162
	2?.'l
	53
	•580
	67

2C
	"17 r
	23 "3
	54
	"597
	68'6

22
	•180
	24'5
	55
	
	70

2 »
	•190
	25-8
	56
	'654
	7 i 'o

24
	'200
	27-1
	57
	"652
	73*2

-5
	'2IO
	28*4
	5^
	•671
	74"7

26
	'220
	29'6
	59
	'69 r
	76-4

27
	*.>3I
	3° '9
	60
	•711
	78' c

28
	'241
	32-2
	6r
	"732
	79'9

29
	'252
	33 "4
	62
	'753
	81 '7

3°
	'263
	34*7
	63
	"774
	84*1

31
	•274
	36
	64
	•796
	36-5      •

32
	
	37 '4
	65
	•8t
	S9'7

33
	•297
	38 S
	66
	•842
	TOO

Pcrct-ta
HNO:S

Sp.gr.

at 15".

c   >

": ^
c   =

.*. *. -^ 4>. -0- J

Percentage
HNOsT"

»- fa -u 3-%-Cj co o B to ui o~4^j vj oo o o •- « »3 oil            at i ^:

Q   tC Ln -q -J O 'Jn  O  CXSM  a, t; \O tn  tJ  O3 ->  O2'-n -<J               »U  1 j .

Percentage

HXO;}.

ll"^

o oa OD      S       II r1

rj ffi
'or.

O

I   t>
i   *tf

i   t>

1       J
350

PRACTICAL ORGANIC CHEMISTRY

V.—TABLE OF SI-ECIKIC GRAVITY AND PKUCENTA<JK OF HVUUOCUI.OKIC ACID
IN A«,>uiious SOLUTION.

5/«

i '060
.1-067
i "075

"'75 j 34 "7
•180 i 35-7
•'«5 I 3<5'8

40-5      |

VI.—TAULK OF SPECIFIC GicAvn'Y AND I'KICCKNTAOI:; oi-* CAUSTIC POTASH IN
Atjuiious SOLUTION.


	'fx .....
	
	Sw
	
	%X
	.   t
	fe-

wi '«•»
	|S
	.J  !•?
	§3
	dl!
	is
	d y
	ll

ffj rt
	
	W   d           _
	OJ '•«
	C/3 rt
	(So
	CO  rt
	

,)(i()
	r
	1-166
	'9      ,
	1 '374
	37
	•s<>-»
	54

-o i 7
	•.j
	1-177
	
	I* ••$<?! 7
	•^Pi
	•604
	55

•<:>•.: 5
	3
	i • 1 88
	'.! I
	1-400
	39
	•618
	56


	4
	r "ryo
	
	r -4 1 '.;
	40
	•6;;5o
	57

"04 t
	5
	1 *'.!09
	-'3
	
	41
	'642
	58

"°49
	6
	I "2'JO
	•^4      :
	i "4 ;P>
	.|.a
	•655
	59-

•, > ,-y
	7
	i '-'30
	-^
	1-450
	43
	•667
	fio

'065
	8
	i "241:
	'j6                !
	i -4')-.:
	44
	•68 1
	6 1

•074
	9
	i'2S~
	'"7
	•r'475
	45
	""95
	fia


	1:1
	i "264
	
	1-488
	46
	"70=)
	63

'09'.!
	i i
	1-1176
	29
	i -499
	47
	•718
	64

'tot
	I '2.
	I -288
	30
	
	48
	•729
	65

*I IO
	13
	1*300
	31
	J '525
	49
	•740
	66

"r 19
	T4
	t"3ir
	3C?
	T "539
	5°
	'754
	67

"liftJ
	T"i
	1-324
	33
	
	">t
	•768 '
	68

''37
	•6
	
	34
	1*565
	5~
	•780
	60

•146
	•7
	i '34Q
	35
	1*578
	53
	•790
	70    .


	18
	T'36r
	36
	
	
	
	

*•*' ******.*
		^        ^          ............_........ ••  Sp.gr.        s
			


		
			

		^                      t      '••  -.  -  C C   :--.^i   z- •-- ..   :;  -  c   ;occ-jjw.  ;:                        -                           ,^                    , ... ..'                  "j                   i                                                                                                         .             T-                \
			
r:   .::.u,,;^-,.^           Percent* CCC   C   -  M -: ^ -ji  -             of X H..
		E "V"                 J
	
	Percentage              ?                 ; of NaOH.               'z                \
	
			o:^j  ~.'^i 4- •_.  :,  —  Z o  ccxa s.'j-; *. ^j  t;  —
		

	
	5                  X
	
	i
	

cc'J"i •; C rv-J 3 M cJi
	bp. gr.
	1        ^                 *~"
	Oj o; j- 'jj '^. -w; ^. •„ '_.j •_-' ••   -   r;   •;  ::   :;  sc  t; VO   30-<s   -Of.-ji -u _.   :i   -,   -•  -2 --4   3- -_r. -^ -^ t;   -
	at 15".                   p
	


		'           :        J>   P
	!          ->   &
		

5 5 3B.;3££§^
	Percenta of NH-;
	S6'   1   l|"
	Ciui iS C^ 1; t; ~c 0   i>=-4   ovji -;I 'J-   ti  U   o 0
	Percentage        E:   < of NaOH.   =      c   -:
	J> r-   nd

i
		"    c 2
	
		'-'W


		^    if ^
	
		

		
	
		

iMCfHf'l
	Sp. gr.
	
	iilliiliMiiiiili i «'^ ! p
		d
 H- 1


	
	5.    ?  l^
	;                      /? _(§!/ •          x
		
^ _ _                    Percenta
		-    i
	
	;    ,,H                   :fr    . Percentage '       ""£                  ,. of NaOH.  it*5'                !i   '
	
0 -H ww^ut 0^ co           of XH-j
		" i n*    >
	tC ^ "S "c o "OTVI "&•£ ^ w 13 "t oo tc^a
		

		
	
	i   '    1 i-?.                   : r    i
	

	
	
	
	;     J.p            :- y
	
VO \D   CC CC>q *vi ^J   ON C\ ui ^ -o -J \O •*>•  O -^ *ji
	Sp. gr.
	s
	^3 IS' Hi 2 il1^ fs ^'^
	Sp.gr.      S    :  r|',                   '..,-•* at I5''       j         Q                 i   ':-r4
	

	
	c
	
	j           t/l'-
	s- V

„ M w 4.0, Cv^ OOG
	Percentage                   % of NH.-jT
		^^^?2^^
	Percentage i           **.     \ of NaOH. !          3,      \
	^


		
	'   ^
		O^

1 ""
Acetaldehyde, 64

Aeetamide, 77     y

AtX'tanilide, 151«/,

AiX'tu: acid, 7.}

Act-tic anhydride, 76

Acetic ether, Sr

AiX'ttuonobromamidt;, 80

AiX'tomx'tic ester, 83

Acetone, 69

Aoetomtrile, 79

Aeeloplicnone, 210

AcRtophenoneoxime, s?i i

Acetophenonesemicarba/one, 212

Acotoxinu.1, 71

Acctyl chloride, 74

Acetylene, 64

Aci-tyl method (Pcrkin), 222

Arrolein, OH

AU;ohoI, 49

Aldehyde-ammonia, 66

Alixartn, ^27

AUnx:ui^i3o

Alhixautiu, 120

Allyl alcohol, IOQ

Aluminium-mercury couple, 213

Amiuoucetic acid, yo

Atuitioaxobenxene, 172

///•Aunrioben/ou: acid, 'jor

/^-Aminoplienol, 146

Ammoniacal cuprous chloride, 64

Aniyl alcohol, 6y

Atnyl nitrite, 69

Aniline. 14 4

Atnsolc, iKl

Ausdiitt/ thermometer, 59

Amhraquinone, 225

Anthnuiuitione      jS-monosxdphonate ot

sodium, aaf*>
AntifeVirin, 151
Appendix, '.134
A/oheuJtene, 145
Axoxybenxene, 143

B

}><:ckina.nn freezing-point apparatus, 33
boiling-point apparatus, 38
thermometer, 34
lleckmann's reaction, at a
Hen/alaniline, 197
^ten/aldehyde, 196
JJenxaUtehyde green, 215

COHEN'S ADV. p. o. c.

ft-P>enzaldoxime, 197
/3-Benxalcloxiiue, 197
lien/amide, 209
Benzene, 136, 162
Hen/ene ethyl sulphonate, 179
Benzene phenyl sulphonate, 179
Benzene sulphonamide, 179
Benzene sulphonanilide, 179
.lienzene sulphonic acid, 177
Benzene sulphonic chloride, 178
Benzidine, 148
Benzil, 203
Benzilic acid, 203
J >enzoic acid, 199
Benzoic ester, 209
I-Jenzoin, 202
Benzoyl cliloride, 208
Ben/oylacetone, 212
Benzyl alcohol, 195, 197
Benzyl chloride, 194
Bisdiazoacetic acid, 96
Bitter almond oil, 190
Riuret, 127^
Boiling-point method, 37
determination of, 58
correction for, 59
^-Bromacetanilide, 152
Bromacetic acid, 89
Bromacetyl bromide, 89
Bromobenzene, 140
7/;-Bromobenzoic acid, sot
Bromocresol, 165
/5-Bromotoluene, 167
Butyric acid, 99
C
Caffeine, 131
Carbamide, 126
Carbamine reaction, 71
Carbolic acid, 179
Carbon, qualitative analysis i
Carbon, quantitative analysis 4
Car Ins' method, 22, 28
Chattaway's reaction, 174
Chloracetic acid, 87
Chloral, 99
Chloral hydrade, 99
Chlorhydrin, in
/•Chloroben/oic acid, 166
Cldoroform, 70
/•Chlorotoluene, 165
('innam,ic acid, 204
Citraconic acid, 125
354

INDEX

3Sj

Citric acid, 124
Claisen flask, 85
Ciaisens reaction, 212
Combustion furnace, 4
Combustion, 4

carbon and hydrogen, 4

nitrogen compounds, 13

substances containing    halogens   and
sulphur, 13

substances containing nitrogen, 12

volatile and hygroscopic substances,

ii

Correction for boiling-point, 59
Creatine, 132
/*-Cresol, 164
Cryoscopic method, 32
Crystallisation, 52
Cuprous chloride, 166
Cyclohexanol, 181

D

Depressimeter, 37
Determination of boiling-point, 58

freezing-point, 33

melting-point, 72

rotatory power, 116

specific gravity, 56
Dextrose, 135
Diazoacetic ester,'94
Diazoaminobenzene, 171
Diazobenzene perbromide, 162
Diazobenzene sulphate, 161
Diazobenzolimide, 232
Dichlorhydrin, 112
Diethyl malonate, 96
Diethyl tartrate, 115
Dihydroxysuccinic acid, 114
Dimethylaniline, 156
Dimethyl oxalate, 101
Dimethyl /-phenylenediamine, 177
Dinaphthol, 220
7/*-Dinitrobenzene, 154
Diphenylhydrazine, 146
Diphenylmethane, 213
Diphenylthipurea, 159
Distillation in steam, 107

in vacuo, 84, 94
Drying apparatus, 4

E

Ebullioscopic method, 37
Electrolytic reduction, oxalic acid, 102

nitrobenzene, 144, 145
Eosin, 187
Epichlorhydrin, in
Estimation of carbon and hydrogen, 4

halogens, 22

nitrogen, 13

sulphur, 28
Ether, 59

commercial, 61
Ethyl acetate, 8r
Ethyl acetoacetate, 83

Ethyl alcohol, 49
Ethyl benzene, 141
Ethyl benzoate, 209
Ethyl bromide, 54
Ethylene bromide, 62
Ethyl ether, 59
Ethyl malonate, 96
Ethyl malonic acid, 97
Ethyl potassium sulphate, 50
Ethyl tartrate,  115
rotation of, 120
Eykman depressimeter, 37

Filter-pump, 44
Filtration through cloth, 131
under reduced pressure, 43
with fluted filter, 53
Fischer's ester method, 133
Fluorescein, 187
Fluted filter, 53
Formic acid, 106
Fractional distillation, 136
Fractionating columns, 137
Freezing-point method, 32
Fried el-Crafts' reaction, 210
Furnace, combustion, 4
tube, 23-;
Fusel oil, 69
G
Gattermann's furnace, 24
diazo-reaction, 167
Gelatine, hydrolysis of, 93
Glucose, 135
Glyceric acid, 100
Glycerin, 106
Glycerol, 106
Glycine, 90
Glycocoll, 90
ester hydrochloride, 92
Glycollic acid, 102
Glyoxylic acid, 102
Grape-sugar, 135
H
Halogens, qualitative determination, 3
quantitative         ,,            32;
Heating under pressure, 78
Hexahydrophenol, 181
Helianthin, 151
Hernpel fractionating column, 137
Hofinann's bottles. 30
Hot-water funnel, 53
Hydrazobenzene, 146
Hydriodic acid, 113
Hydrobenzamide, 596
Hydrobromic acid, 140
Hydrochloric acid gas, 93
Hydrocinnamic acid, 204
Hydrogen, qualitative determination, r
quantitative          },          f
INDEX

355

Hydrolysis of ethyl acetate, 82
I lydroquinont', jfoj
<>4Iydroxybcn/alddiyde, r8S
/                  „                  i33

Hydroxyben/ene, rjg
0-Hydi'oxyben/oie acid, ig<,»
m-          ,,              ,,     200

Hydroxyl method ('f$c/ntga.fjff\ 223
Hypnotic, 2iOj

1

lodoben/ene, 163
T,odoform reaction, 50      ,,}
lodosutolnene, ifio.          .t,/^

/-lodotolueuo, 168
I sat in, 220
Isopropyl iodide, uo

Kjeldaftfs method, 20

I.

f*ttin'?n?$ pulariuirtcT, 116

LeuciiH", i \\

IJcherinann's nitruso reaction, 159

M

Malachite j/jwrn, "i$
Malic add, i r.r
Malonii: csitrr, !U
MaiuU'lic arid, ;:«i^
Mcluiij^-^oiut^ d«'tcnnit:atiou, 72

Mcsoiartaric ;u.;id, ia;s

Methyl *u:i»tatf, Bi
Methyl aU:oholj 67
Methyl alcoholic potash, 57
Mctltylaminr hydrochloritlir, 80
Methylated spirit, purification of, 4*3
Mfthyl t'yauid**, 71)
Methyloncamihi >'art;tonitril«, 93
Methyl iotlitlt.*, nH
Methyl or;mj<«.% 17*)
Methyl oxalutc;, mi
Methyl phenatc, jSi
Methyl potassititn sulphate, 5"
Molecular mtatton, 119
Molecular \v«»i^ht, - -
vapour (l«Mi.ttty, 39

oruanic liases, 40

^/*l//4't://',v reac'tjon, r i?5
Monobroinm.'etic acitl, 89
Monochlonufittic aud, 87
Mhruxrhlorhydritt, x x i

Mtstexide, 139

N

Naphthalene, 216
Naphthalene picrate, 217
Naphthalene sulphonate of'sodium, 218-
/i-Naphthol, 219
Naphthol yellow, 224
/i-Naphthyl acetate, 222
/i-NTaphthyl methyl ether, 220
/-Nitracetanilide, 153
w-Nitraniline, 154
/•Nitraniline, 153    .
Nitric acid (fuming), 22
Nitrobenzene, 142
w-Nitrobeiwoic acid, 200
Nitrogen, qualitative estimation, z

quantitative estimation, 13
Nitrophenol, 183
Nitrosobenzene, 146
/-Nitrosodimethylaniline, 157
.Nitrosophenol, 159

Organic analysis, i
Oxalic acid, 100
Oxamidc, 102
Oxanthranolatc of sodium, 226

Palmitic acid, 104
Palm oil, 104
Paraldehyde, 67
Pararosaniline, at«;
Perkints acctyl method 222
Perkin's pyknometer, 57
Phenol, 179
Phenolphthalein, 186
Phcnylacctatnidc; 15 r
Phenylacrylic acid, 204
Plicnyl bromide, 140
///•Phenylenediamine, 155
/-Phenyjenediamine, 173
Phenyl isocyanate, 160
Phenylhydraxine, 173
Phenylhydroxylaminci, T48
Phenyl mustard oil, 160
Phenyl -methyl carhinol, 206
Phenyl methyl ether, i8t
Phenyl methyl ketone, 210
Phenyl methyl pyrasrolone, 175
Phenyl   methyl   triuxolecarboxylic   acid,,
233
Phenylpropionic acid, 204
Phenylthiocarbimide, 160
Phcuylthiourethane, 160
Phosphorus, qualitative analysis, 3
Phthalie acid, 317
Picric acid, 185 •
Piria &* Schiff's method, vt
Polarimt'ter, "u6
Potash apparatus, 4
>     f

356

INDEX

Potassium benzene sulphonate, 177
Potassium ethyl sulphate, 50
Potassium methyl sulphate, 50
Preparations, general remarks, 47
Pressure tube, glass, 24, 78

furnace, 24

metal, 227
Purification of ether, 60

methylated spirit, 4 3
Pyknometer, 57
Pyruvic acid, 124

Quantitative   estimation   cf   carbon   and

hydrogen, 4
halogens, 22

nitrogen, 13                           *

sulphur, 28
_uinine sulphate 231
^uinol, 193
^uinoline, 230

8uinone, 102               ••                   '         -

^uinoneoxime, 159                            „  , . ,

Tartaric acid, 114
Terephthalic acid, 171
Tetrabromocresol, 165
Thiocarbamide, 128
Thiocarbanilamide, 159
Thiocarbanilide, 159
Thiourea, 128
/-Tolyl bromide, 167
/-Tolyl chloride, 165
/-Tolyl cyanide, 169
Tolyliodochloride, 169
Toluene from toluidine, 163
j7$-Toluic acid, 170
Tribromophenol, 180
Trichloracetic acid, 99
Trimethylxan thine, 131
Trinitrophenol, 185
Triphenylguanidine, 160
Triphenylmethane, 2:4
Tschugctcff's hydroxyl methqd, 223
'Tube furnace, 23
•Tyrosinej 133

Racemic acid, '122-,

resolution of, -123
T? ing-burner, 108
Rotation of ethyl tartrate, 120

tartaric acid, 120    •   .

•       U .

-.yibnanrfs reaction, 180
Ur6a, 126
Uric, acid, 128

"Salicylaldehyde, 188
Salicylic acid, 190
Sandtneyers reaction, 165, 167
Saponification of ethyl acetate, 82

palm oil, 104
Schiff's azotometer, 14

reaction, 67

Schotten-Buwnanrfs reaction, 209
Sealed tube furnace, 23
•Sealed tubes, 24
Sodium bisulphite, 67

knife, 61

press, 61

Specific gravity determination, 56
Specific rotation, 1-19 -,
Spirits of wine, purification of, 49
Sprenget's pyknometjly, 57
Succinic acid, 113         f

Sulphanilic acid, 175 ^
Sufehur, estimation ,of, 28

&F      ,,'

Y^cuum-desiccator, 45
Vacuum distillation, 84, 94
Vapour density method, 29
Victor-Meyer Apparatus, 29
Vigreux's fractionating column, 137

Water-jet aspirator, 44
Water turbine, 91

Young and Thomas fractionating column
137